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                                                                    Exhibit 10.4

                       FIRST AMENDMENT TO REVOLVING CREDIT
                             AND TERM LOAN AGREEMENT

      THIS FIRST AMENDMENT TO REVOLVING CREDIT AND TERM LOAN AGREEMENT (this
"AMENDMENT") dated as of October 31, 2005, is entered into by and among ATLAS
PIPELINE PARTNERS, L.P., a Delaware limited partnership ("BORROWER"); ATLAS
PIPELINE NEW YORK, LLC, a Pennsylvania limited liability company ("APL NEW
YORK"); ATLAS PIPELINE OHIO, LLC, a Pennsylvania limited liability company ("APL
OHIO"); ATLAS PIPELINE PENNSYLVANIA, LLC, a Pennsylvania limited liability
company ("APL PENNSYLVANIA"); ATLAS PIPELINE OPERATING PARTNERSHIP, L.P., a
Delaware limited partnership ("APL OPERATING"); ATLAS PIPELINE MID-CONTINENT
LLC, a Delaware limited liability company ("APL MID-CONTINENT"); ELK CITY
OKLAHOMA PIPELINE, L.P., a Texas limited partnership ("ELK CITY"); ELK CITY
OKLAHOMA GP, LLC, a Delaware limited liability company ("ELK CITY GP"); and
ATLAS ARKANSAS PIPELINE LLC, an Oklahoma limited liability company ("ATLAS
ARKANSAS"; Atlas Arkansas, Elk City GP, Elk City, APL Mid-Continent, APL New
York, APL Ohio, APL Pennsylvania and APL Operating are collectively referred to
herein as the "GUARANTORS," and Borrower and Guarantors are collectively
referred to herein as the "OBLIGORS"); each of the lenders party hereto
(individually, together with its successors and assigns, a "LENDER," and
collectively, "LENDERS"); and WACHOVIA BANK, NATIONAL ASSOCIATION, as
administrative agent for the Lenders (in such capacity, together with its
successors in such capacity, "ADMINISTRATIVE AGENT").

                                 R E C I T A L S

      A. Borrower, certain Guarantors, Administrative Agent and the Lenders have
entered into that certain Revolving Credit and Term Loan Agreement dated as of
April 14, 2005 (as renewed, extended, amended or restated from time to time, the
"CREDIT AGREEMENT").

      B. Borrower has entered into that certain Stock Purchase Agreement (as
amended, supplemented, restated or otherwise modified prior to the date hereof,
the "STOCK PURCHASE AGREEMENT") dated of even date herewith, with Enogex Inc.,
an Oklahoma corporation ("ENOGEX"), whereby Borrower will purchase from Enogex
all of the issued and outstanding common stock of Atlas Arkansas (the "SHARES";
the acquisition of the Shares contemplated by the Stock Purchase Agreement is
herein called the "ATLAS ARKANSAS ACQUISITION").

      C. In order to facilitate the Atlas Arkansas Acquisition, Borrower has
requested that Administrative Agent and the Lenders amend certain provisions of
the Credit Agreement to, among other things, increase the Aggregate Maximum
Revolver Amount.

      D. Administrative Agent and the Lenders have agreed to amend the Credit
Agreement as so requested, subject to the terms and conditions set forth herein.

      NOW, THEREFORE, in consideration of the foregoing, and intending to be
legally bound, the parties agree as follows:

      SECTION 1. TERMS DEFINED IN CREDIT AGREEMENT. As used in this Amendment,
except as may otherwise be provided herein, all capitalized terms which are
defined in the Credit Agreement shall have the same meaning herein as therein,
all of such terms and their definitions being incorporated herein by reference.

      SECTION 2. AMENDMENTS TO CREDIT AGREEMENT. Subject to the conditions set
forth in SECTION 3 hereof, the Credit Agreement is hereby amended as follows:

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      (a) Section 1.02 of the Credit Agreement (Definitions) is hereby amended
as follows:

            (i) The definition of "AGGREGATE MAXIMUM REVOLVER AMOUNT" is hereby
      restated in its entirety to read as follows:

                  "AGGREGATE MAXIMUM REVOLVER AMOUNT at any time shall equal the
            sum of the Maximum Revolver Amounts of the Revolver Lenders (Four
            Hundred Million Dollars ($400,000,000)), as the same may be
            increased pursuant to SECTION 2.11 or reduced pursuant to SECTIONS
            2.03(a) or 2.07(b)(i)."

            (ii) The definition of "CONSOLIDATED EBITDA" is hereby restated in
      its entirety to read as follows:

            "CONSOLIDATED EBITDA shall mean, for any trailing twelve-month
            period, the sum of (i) Consolidated Net Income for such period, plus
            (ii) the following expenses or charges to the extent deducted from
            Consolidated Net Income in such period: interest, income taxes,
            depreciation, depletion, amortization, non-cash compensation on
            long-term incentive plans, and other non-cash charges to
            Consolidated Net Income, minus (iii) non-cash credits to
            Consolidated Net Income, provided, that, the following adjustments
            shall be made: (a) Consolidated EBITDA for each quarter of 2005
            shall be calculated after giving pro forma effect to the Elk City
            Acquisition and the adjustments described on SCHEDULE 1.01 hereto;
            and (b) the amount of Consolidated EBITDA attributable to Atlas
            Arkansas' interest in NOARK shall be (1) for the four fiscal
            quarters ending September 30, 2005, $13,133,000, and (2) for each of
            the four fiscal quarters ending December 31, 2005, March 31, 2006,
            and June 30, 2006, (A) for periods prior to October 31, 2005,
            Consolidated EBITDA of Atlas Arkansas minus Maintenance Capital
            Expenditures of Atlas Arkansas, and (B) on or after October 31,
            2005, the amount of cash distributions received.

            For purposes hereof, "MAINTENANCE CAPITAL EXPENDITURES" shall mean
            without duplication for any period, the aggregate of all capital
            expenditures related to the Pipeline determined in accordance with
            GAAP, excluding (a) expenditures in respect of any transaction or
            any series of related transactions to acquire any asset, the
            acquisition of which is not made to maintain or improve an existing
            asset and (b) expenditures of any proceeds of any insurance,
            condemnation award or other compensation paid or payable in respect
            of any loss or damage to or any condemnation or taking of, any
            capital asset less the reasonable fees, taxes and expenses paid to
            collect such proceeds, to rebuild or repair such Pipeline equipment
            or such other asset."

            (iii) The definition of "CONSOLIDATED FUNDED DEBT" is hereby amended
      by deleting clause (vii) thereof in its entirety, and replacing it with
      the following:

                  "(vii) until March 31, 2006, Consolidated Funded Debt shall be
            calculated excluding debt evidenced by the NOARK Notes; thereafter,
            to the extent that Atlas Arkansas' portion of the NOARK Notes has
            not been repurchased, such portion shall be included in such
            calculations; SWPL's portion of the NOARK Notes shall not be
            included in such calculations at any time."

            (iv) The definition of "CONSOLIDATED INTEREST EXPENSE" is hereby
      amended by deleting the word "and" before clause (iii) thereof, and adding
      the following clause after the word "quarters" at the end of such clause
      (iii):

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            "; and (iv) until March 31, 2006, Consolidated Interest Expense
      shall be calculated excluding debt evidenced by the NOARK Notes;
      thereafter, to the extent that Atlas Arkansas' portion of the NOARK Notes
      has not been repurchased, such portion shall be included in such
      calculations; SWPL's portion of the NOARK Notes shall be excluded from
      such calculations; provided, however, such portion shall be included in
      such calculations to the extent Atlas Arkansas or any other Obligor makes
      any interest payment with respect to such portion or assumes, directly or
      indirectly, any liability for any interest payment with respect to such
      portion"

            (v) The definition of "GUARANTOR" is hereby restated in its entirety
      to read as follows:

                  "GUARANTOR shall mean each Initial Guarantor and each
            Subsidiary of Borrower hereafter formed or acquired, except for the
            Unrestricted Entities (if any) and NOARK (unless and until NOARK
            becomes a Wholly Owned Subsidiary."

            (vi) The definition of "LC COMMITMENT" is hereby amended by
      replacing the words "Ten Million Dollars ($10,000,000)" therein with the
      words "Fifty Million Dollars ($50,000,000)".

            (vii) The definition of "MASTER NATURAL GAS GATHERING AGREEMENTS" is
      hereby restated in its entirety as follows:

                  "MASTER NATURAL GAS GATHERING AGREEMENTS shall mean those
            agreements listed as ITEMS 2, 3, 4, 5 and 6 on SCHEDULE 7.23, as
            such agreements may be amended, extended, renewed or replaced from
            time to time."

            (viii) The definition of "PIPELINES" is hereby restated in its
      entirety as follows:

                  "PIPELINES shall mean the natural gas transportation systems
            and gas gathering systems and related processing facilities now
            owned and operated (or in the case of the NOARK Pipeline, operated)
            as private use gathering systems by the Obligors located in the
            states of New York, Ohio, Pennsylvania, Oklahoma, Missouri and
            Texas, and all additions thereto, and such other natural gas
            gathering systems and related processing facilities owned and
            operated (or in the case of the NOARK Pipeline, operated) by the
            Obligors hereafter."

      (b) The following definitions are hereby added to Section 1.02 of the
Credit Agreement where alphabetically appropriate:

            (i) "ATLAS ARKANSAS means Atlas Arkansas Pipeline LLC, an Oklahoma
      limited liability company."

            (ii) "NOARK means NOARK Pipeline System, Limited Partnership, an
      Arkansas limited partnership."

            (iii) "NOARK FINANCE means NOARK Pipeline Finance, L.L.C., an
      Oklahoma limited liability company, a wholly-owned subsidiary of NOARK."

            (iv) "NOARK NOTES means (i) the 7.15% Notes due 2018 issued by NOARK
      Finance pursuant that certain Indenture dated as of June 1, 1998, between
      NOARK Finance and The Bank

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      of New York, as trustee, and (ii) the related Loan Agreement dated as of
      June 1, 1998, between NOARK, as borrower, and NOARK Finance, as lender."

            (v) "NOARK PARTNERSHIP AGREEMENT means that certain Amended and
      Restated Agreement of Limited Partnership of NOARK dated January 12, 1998
      (as the same may be amended, restated, or otherwise modified from time to
      time).

            (vi) "NOARK PIPELINE means the natural gas transportation system and
      gas gathering systems owned by NOARK."

            (vii) "SWPL means Southwestern Energy Pipeline Company, an Arkansas
      corporation."

      (c) Section 2.07 of the Credit Agreement (Prepayments) is hereby amended
by replacing subsections (b) and (c) thereof with the following:

            "(b) MANDATORY PREPAYMENTS.

                  (i) Borrower shall prepay the Revolver Principal Debt in an
            amount equal to 100% of Net Cash Proceeds up to an aggregate amount
            of One Hundred Seventy-Five Million Dollars ($175,000,000), not
            later than the third Business Day following the receipt thereof. The
            Aggregate Maximum Revolver Amount shall be permanently reduced by
            the amount of each such prepayment made pursuant to this SECTION
            2.07(b)(i).

                  (ii) Thereafter, Borrower shall prepay the Principal Debt in
            an amount equal to Net Cash Proceeds required to maintain a Senior
            Secured Leverage Ratio of 4.00 to 1.00 or less, not later than the
            third Business Day following receipt of such Net Cash Proceeds.

                  (iii) Notwithstanding CLAUSES (i) and (ii) above, following
            mandatory prepayments under CLAUSE (i) in an aggregate of One
            Hundred Million Dollars ($100,000,000) of Equity Net Cash Proceeds,
            the receipt by Borrower of subsequent Equity Net Cash Proceeds of up
            to $40,000,000 shall not trigger a mandatory prepayment of Principal
            Debt to the extent such proceeds are used to fund the construction
            of the Sweetwater gas plant in Beckham County, Oklahoma, and
            associated gathering and pipeline interconnects.

            (c) GENERALLY. Prepayments permitted under this SECTION 2.07 shall
      be without premium or penalty, except as required under SECTION 5.05 for
      prepayment of LIBOR Loans. Any voluntary prepayment of the Principal Debt
      shall be applied to the Revolver Principal Debt and the Term Loan
      Principal Debt at the Borrower's discretion; provided, that upon any
      Default or Event of Default, any such prepayment shall be allocated pro
      rata to each Revolver Lender and each Term Loan Lender in accordance with
      its Percentage Share of the Principal Debt. Any mandatory prepayment of
      the Principal Debt under CLAUSE (b)(ii) above shall be applied first
      against the Term Loan Principal Debt, and the balance, if any, shall be
      applied against the Revolver Principal Debt. With respect to the Revolver
      Loans, any mandatory prepayments made pursuant to CLAUSE (b)(ii) above and
      any voluntary prepayments may be reborrowed subject to the then effective
      Aggregate Maximum Revolver Amount."

      (d) The following is hereby added to the Credit Agreement as SECTION 2.11:

                  "Section 2.11     INCREASE IN REVOLVER FACILITY.

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                           (a) Provided there exists no Default and subject to
                  the conditions set forth under CLAUSE (e) below, upon notice
                  to the Administrative Agent (which shall promptly notify the
                  Lenders), Borrower may from time to time request an increase
                  in the aggregate Revolver Commitments under the Revolver
                  Facility; provided, that (i) the Aggregate Maximum Revolver
                  Amount shall not exceed $475,000,000, and (ii) such increase
                  of the Revolver Facility shall be in a minimum amount of
                  $25,000,000, or integral multiples of $1,000,000 in excess
                  thereof. At the time of sending such notice, Borrower (in
                  consultation with the Administrative Agent) shall specify the
                  time period within which each Revolver Lender is requested to
                  respond.

                           (b) Each Revolver Lender shall notify the
                  Administrative Agent within such time period whether or not it
                  agrees to increase its Revolver Commitment and, if so, whether
                  by an amount equal to, greater than, or less than its
                  Percentage Share of such requested increase. Any Revolver
                  Lender not responding within such time period shall be deemed
                  to have declined to increase its Revolver Commitment.

                           (c) The Administrative Agent shall notify Borrower of
                  the Revolver Lenders' responses to the request made hereunder.
                  To achieve the full amount of a requested increase and subject
                  to the approval of the Administrative Agent and the Issuing
                  Bank (which approvals shall not be unreasonably withheld),
                  Borrower may also invite additional Eligible Assignees to
                  become Revolver Lenders pursuant to a joinder agreement in
                  form and substance satisfactory to the Administrative Agent
                  and its counsel.

                           (d) If the aggregate Revolver Commitments are
                  increased in accordance with this Section, the Administrative
                  Agent and Borrower shall determine the effective date (such
                  date, the "INCREASE EFFECTIVE DATE") and the final allocation
                  of such increase. The Administrative Agent shall promptly (i)
                  notify Borrower of the final allocation of such increase in
                  the Revolver Commitment and the Increase Effective Date, and
                  (ii) notify each Revolver Lender of its Revolver Commitment as
                  of the Increase Effective Date.

                           (e) As a condition precedent to such increase,
                  Borrower shall deliver to the Administrative Agent a
                  certificate of each Obligor dated as of the Increase Effective
                  Date signed by a Responsible Officer of such Obligor (i)
                  certifying and attaching the resolutions adopted by such
                  Obligor approving or consenting to such increase, and (ii) in
                  the case of Borrower, certifying that, before and after giving
                  effect to such increase, (A) the representations and
                  warranties contained in ARTICLE VII and the other Loan
                  Documents are true and correct on and as of the Increase
                  Effective Date, except to the extent that such representations
                  and warranties specifically refer to an earlier date, in which
                  case they are true and correct as of such earlier date, and
                  except that for purposes of this SECTION 2.11, the
                  representations and warranties contained in SECTION 7.02 shall
                  be deemed to refer to the most recent statements furnished
                  pursuant to CLAUSES (a) and (b), respectively, of SECTION
                  8.01, (B) no Default exists, (C) no Material Adverse Effect
                  shall have occurred, and (D) the Senior Secured Leverage Ratio
                  does not exceed 4.00 to 1.00. To the extent necessary to keep
                  the outstanding Revolver Loans ratable with any revised
                  Percentage Shares of the Revolver Lenders arising from any
                  nonratable increase in the Revolver Commitments under this
                  Section, Borrower shall prepay Revolver Loans outstanding on
                  the Increase Effective Date and/or Lenders shall make
                  assignments pursuant to arrangements satisfactory to the
                  Administrative Agent (provided, that in each case, Borrower
                  shall pay any additional amounts required pursuant to SECTION
                  5.05).

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<PAGE>

                        (f) This Section shall supersede any provisions in
            SECTIONS 4.05 or 12.04 to the contrary."

      (e) Section 4.05(a) of the Credit Agreement (Set-off) is hereby amended by
adding the following after the word "Subsidiary" therein:

            "(except for NOARK, unless and until NOARK becomes a Wholly Owned
      Subsidiary)"

      (f) Section 7.07 of the Credit Agreement (Use of Loans) is hereby amended
by replacing clause (iii) therein with the following:

            "(iii) for the development of the Pipeline Properties and the
      acquisition of Pipeline Properties and related assets (or equity interests
      therein) by the Obligors"

      (g) Section 8.01 of the Credit Agreement (Reporting Requirements) is
hereby amended by deleting the phrase "and consolidating" each time it appears
in subsections (a) and (b) thereof.

      (h) Section 8.01 of the Credit Agreement (Reporting Requirements) is
hereby amended by replacing subsection (e) thereof with the following:

            "(e) REGULATORY FILINGS, ETC. Promptly upon its becoming available,
      (i) each financial statement, report, notice or proxy statement sent by
      the Borrower to its unitholders generally and each regular or periodic
      report and any registration statement, prospectus or written communication
      (other than transmittal letters) in respect thereof filed by the Borrower
      with or received by the Borrower in connection therewith from any
      securities exchange or the SEC or any successor agency; and (ii) each
      report, notice, request, application, or other filing or material
      communication that is filed by the Borrower with or received by the
      Borrower from the Federal Energy Regulatory Commission or any successor
      agency."

      (i) Section 8.03(c) of the Credit Agreement is hereby amended by adding
the following sentence at the end thereof:

            "Notwithstanding the foregoing, for so long as NOARK is not a
Wholly-Owned Subsidiary, the obligations of Atlas Arkansas under this SECTION
8.03(c) with respect to the NOARK Pipeline shall be limited to actions that
Atlas Arkansas is required to take under the NOARK Partnership Agreement."

      (j) Section 8.07 of the Credit Agreement (Reserve Reports) is hereby
restated in its entirety to read as follows:

            "Section 8.07     [Reserved]"

      (k) Section 8.09(a) of the Credit Agreement (Lien on Pipeline Properties)
is hereby amended by adding the following parenthetical at the end of the first
sentence thereof:

            "(except with respect to Pipeline Properties of NOARK, unless and
      until NOARK becomes a Wholly Owned Subsidiary)"

      (l) Section 8.09(d) of the Credit Agreement (Subordination of Obligors'
Liens) is hereby amended as follows:

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            (i) Subsection (iii) thereof is hereby amended by adding the
      following parenthetical after the words "Pipeline Properties":

            "(except for such Pipeline Properties that are not Mortgaged
      Properties)"

            (ii) Subsection (v) thereof is hereby amended by adding the
      following parenthetical after the word "Pipelines":

            "(except for the NOARK Pipeline, for so long as such Pipeline is not
      a Mortgaged Property)"

      (m) Section 8.13 of the Credit Agreement (Guaranties) is hereby amended by
replacing the phrase "(other than the Unrestricted Entities)" therein with the
following phrase:

            "(other than the Unrestricted Entities and other than NOARK, unless
      and until NOARK becomes a Wholly Owned Subsidiary)"

      (n) The following is hereby added to the Credit Agreement as Section 8.15:

            "8.15 NOARK DEBT. Borrower shall not permit Atlas Arkansas to
      extend, increase, or modify any Debt of NOARK existing as of October 31,
      2005, or cause, permit, or approve additional Debt of NOARK after such
      date, except for Debt of the type permitted in Sections 9.01(a), (c), (d)
      ,(e), (f), (g), (j), and (k)."

      (o) Section 9.01 of the Credit Agreement (Debt) is hereby amended by
renaming clause (j) thereof as "clause (l)" and replacing clause (i) thereof
with the following:

            "(i) Debt in an amount not to exceed Two Hundred Seventy-Five
      Million Dollars ($275,000,000) incurred in connection with a senior or
      subordinated unsecured note offering with a maturity date at least one
      year beyond the maturity of the Facilities, the documentation for which
      contains covenants no more restrictive than those set forth in this
      Agreement; and

            (j) unsecured guarantees of Subsidiary obligations (other than
      obligations for borrowed money); and

            (k) Debt evidenced by the NOARK Notes; and"

      (p) Section 9.03(i) of the Credit Agreement (Investments, Loans and
Advances) is hereby amended by replacing the words "Fifteen Million Dollars
($15,000,000)" therein with the words "Fifty Million Dollars ($50,000,000)".

      (q) Section 9.13 of the Credit Agreement is hereby restated in its
entirety to read as follows:

            "Section 9.13 CONSOLIDATED EBITDA TO CONSOLIDATED INTEREST EXPENSE.
      Borrower will not permit the ratio of its Consolidated EBITDA to
      Consolidated Interest Expense as of the end of any fiscal quarter of
      Borrower (calculated quarterly based upon the four most recently completed
      quarters) to be less than:

               October 1, 2005 through March 30, 2006           2.50 to 1.00
               March 31, 2006 and thereafter                    3.00 to 1.00"

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      (r) Section 9.14 of the Credit Agreement is hereby restated in its
entirety to read as follows:

            "Section 9.14 CONSOLIDATED FUNDED DEBT TO CONSOLIDATED EBITDA. The
      Borrower will not permit the ratio of its Consolidated Funded Debt to
      Consolidated EBITDA (the "LEVERAGE RATIO") as of the end of any fiscal
      quarter of the Borrower (calculated quarterly based upon the four most
      recently completed quarters, and including pro forma adjustments
      acceptable to the Administrative Agent following any material acquisition)
      set forth below to be more than the ratio corresponding to such periods:

               October 1, 2005 through March 30, 2006           6.00 to 1.00
               March 31, 2006 through June 29, 2006             5.75 to 1.00
               June 30, 2006 and thereafter                     4.50 to 1.00"

      (s) Section 9.15 of the Credit Agreement is hereby restated in its
entirety to read as follows:

            "Section 9.15 CONSOLIDATED SENIOR SECURED DEBT TO CONSOLIDATED
      EBITDA. The Borrower will not permit the ratio of its Consolidated Senior
      Secured Debt to Consolidated EBITDA (the "SENIOR SECURED LEVERAGE RATIO")
      as of the end of any fiscal quarter of the Borrower (calculated quarterly
      based upon the four most recently completed quarters, and including pro
      forma adjustments acceptable to the Administrative Agent following any
      material acquisition) set forth below to be more than the ratio
      corresponding to such periods:

              October 1, 2005 through March 30, 2006            6.00 to 1.00
              March 31, 2006 through June 29, 2006              5.75 to 1.00
              June 30, 2006 through September 29, 2006          4.50 to 1.00
              September 30, 2006 and thereafter                 4.00 to 1.00"

      (t) Section 10.01 of the Credit Agreement (Events of Default) is hereby
amended by adding the following to the end of subsection (b) thereof:

            "(iii) Any event specified in any note, agreement, indenture or
      other document evidencing or relating to the NOARK Notes shall occur if
      the effect of such event is to cause the holder or holders of such Debt
      (or a trustee or agent on behalf of such holder or holders) to cause such
      Debt in excess of $25,000,000 to become due prior to its stated maturity;
      or"

      (u) Subsections (e), (f), and (g) of Section 10.01 of the Credit Agreement
are hereby amended by adding the words "or NOARK" after the word "Obligor" each
time such word appears in such subsections.

      (v) Atlas Arkansas is hereby added as a "Guarantor" and an "Obligor" under
the Credit Agreement.

      SECTION 3. AMENDMENT EFFECTIVE DATE. This Amendment shall be binding upon
all parties to the Credit Agreement as of the date (the "AMENDMENT EFFECTIVE
DATE") that Administrative Agent receives the following (other than (a) Atlas
Arkansas' organizational documents under CLAUSE (c) below, and (b) the Opinion
of Pray, Walker, Jackman, Williamson & Marlar, Oklahoma counsel to the Borrower,
which items are hereby permitted to be delivered after the Amendment Effective
Date but no later than one Business Day following the acceptance of such
organizational documents by the Oklahoma Secretary of State, or such later date
as the Administrative Agent may agree):

                                       8
<PAGE>

      (a) sufficient counterparts of this Amendment, executed and delivered to
Administrative Agent by (i) each Obligor, (ii) Administrative Agent, (iii)
Issuing Bank, and (iv) each Lender;

      (b) replacement Revolver Notes, reflecting the Lenders' revised Revolver
Commitments;

      (c) From each Obligor, such certificates of secretary, assistant
secretary, manager, or general partner, as applicable, as the Administrative
Agent may require, certifying (i) resolutions authorizing the execution and
performance of (A) this Amendment and the other Loan Documents that such Person
is executing in connection herewith, and (B) the Stock Purchase Agreement and
each other agreement, document and instrument executed and delivered by Borrower
or any other Obligor and any counterparty thereto in connection with the Atlas
Arkansas Acquisition, as applicable (collectively, the "ATLAS ARKANSAS
ACQUISITION DOCUMENTS"), (ii) the incumbency and signature of the officer
executing such documents, and (iii) that there has been no change in such
Person's organizational documents since April 14, 2005 (or, if there has been a
change, and in the case of Atlas Arkansas' organizational documents attaching a
copy thereof);

      (d) A copy of the Atlas Arkansas Acquisition Documents, including without
limitation the Escrow Agreement pursuant to which Enogex agrees to deposit into
an escrow or similar account an amount sufficient to repurchase the portion
guaranteed by Enogex of the 7.15% Notes due 2018 issued pursuant that certain
Indenture dated as of June 1, 1998, between NOARK Pipeline Finance, L.L.C., and
The Bank of New York, as trustee, and all schedules and exhibits to such Atlas
Arkansas Acquisition Documents (as supplemented or amended prior to the
Amendment Effective Date), certified by Borrower as true and complete, in form
and substance reasonably satisfactory to the Co-Lead Arrangers;

      (e) A duly completed compliance certificate, dated as of the Amendment
Effective Date, substantially in the form of Exhibit C to the Credit Agreement,
demonstrating pro forma compliance with Sections 9.13, 9.14, and 9.15 of the
Credit Agreement as of the end of the most recent fiscal quarter for which
Borrower is required to provide financial statements pursuant to Section 8.01 of
the Credit Agreement, after giving effect to the Atlas Arkansas Acquisition and
after giving effect to any Indebtedness (including the obligations under the
Credit Agreement and the other Loan Documents) incurred in connection therewith;

      (f) Such financial statements of NOARK Pipeline System, Limited
Partnership ("NOARK"), as may be reasonably requested by Co-Lead Arrangers;

      (g) A certificate signed by a Responsible Officer of Borrower, dated as of
the Amendment Effective Date, certifying (a) that the closing of the Atlas
Arkansas Acquisition is being consummated on such date; (b) additions as
applicable to the Annexes to each Pledge, Assignment, and Security Agreements
previously executed by the Obligors to reflect ownership of the Shares; (c)
revised Schedules to the Credit Agreement, as applicable; (d) that after giving
effect to this Amendment and the revised Schedules to the Credit Agreement and
Annexes to the Pledge, Assignment, and Security Agreements, both before and
after taking into account the Atlas Arkansas Acquisition and the funding of
Loans on such date, the representations and warranties contained in Article VII
of the Credit Agreement and in the Security Instruments are true and correct in
all material respects on and as of such date except to the extent such
representations and warranties relate solely to an earlier date; (e) that after
giving effect to this Amendment, both before and after giving effect to the
Atlas Arkansas Acquisition, no Default or Event of Default has occurred and is
continuing as of such date; (f) that since December 31, 2004, there has occurred
no "Material Adverse Effect" (as such term is defined in the Stock Purchase
Agreement) with respect to the Borrower; (g) that there is no litigation,
investigation or proceeding known to and affecting Borrower or any Affiliate of
Borrower for which Borrower is required to give notice pursuant to Section 8.02
of the Credit Agreement; and (h) that there are no actions, suits,
investigations or

                                       9
<PAGE>

proceedings pending or, to the knowledge of Borrower, threatened in any court or
before any arbitrator or governmental authority by or against Borrower, any
Guarantor, or any of their respective properties, that (i) if adversely
determined, could reasonably be expected to materially and adversely affect
Borrower, any Guarantor, or the Mortgaged Property, taken as a whole, or the
Shares, or (ii) seek to affect or pertain to any transaction contemplated
hereby, the Atlas Arkansas Acquisition, or the ability of Borrower or any
Guarantor to perform its obligations under the Loan Documents;

      (h) The Security Instruments listed on SCHEDULE 1 hereto, duly completed
and executed in sufficient number of counterparts for recording, if necessary,
including delivery of any requisite mortgage tax affidavit and payment for
applicable mortgage tax, if any due; all original certificates of partnership
units or members' equity, blank stock powers, and Intercompany Notes duly
endorsed as required under such Security Instruments.

      (i) A Guaranty Agreement executed by Atlas Arkansas in favor of the
Administrative Agent, for the benefit of the Lenders;

      (j) A certificate of a Responsible Officer of Borrower, dated as of the
Amendment Effective Date, (a) listing the Material Agreements executed in
connection with, or assumed in connection with, the Atlas Arkansas Acquisition,
and (b) certifying that Borrower has no knowledge of any material default
thereunder by any party thereto;

      (k) An opinion of counsel to the Obligors (including local counsel)
acceptable to the Co-Lead Arrangers, with respect to the existence of the
Obligors, due authorization and execution of the Amendment, the Atlas Arkansas
Acquisition Documents, and the other Loan Documents executed in connection
therewith, enforceability of the Amendment, the Atlas Arkansas Acquisition
Documents, and such Loan Documents, including without limitation the Security
Instruments, under the laws of the states wherein the Mortgaged Properties are
located, and other matters incident to the transactions herein contemplated as
the Co-Lead Arrangers may reasonably request, each in form and substance
satisfactory to the Co-Lead Arrangers;

      (l) Title information as the Co-Lead Arrangers may require setting forth
the status of title to the Properties (including, without limitation, the
Pipeline Properties (including title to the Pipelines owned by NOARK))
acceptable to the Co-Lead Arrangers;

      (m) Appropriate UCC search certificates and other evidence satisfactory to
the Co-Lead Arrangers with respect to the Obligors' Properties reflecting no
prior Liens, other than Excepted Liens;

      (n) Environmental assessments and other reports to the extent maintained
by the Atlas Arkansas or NOARK covering NOARK's Properties, reporting on the
current environmental condition of such Properties, satisfactory to the Co-Lead
Arrangers and the Lenders;

      (o) A letter from CT Corporation System, Inc., or other agent acceptable
to the Administrative Agent, accepting service of process in the State of New
York on behalf of Atlas Arkansas; and

      (p) such other agreements, certificates, documents and evidence of
authority as Co-Lead Arrangers, any Lender or counsel to the Co-Lead Arrangers
may reasonably request.

      SECTION 4. REPRESENTATIONS AND WARRANTIES OF OBLIGORS. Each of the
Obligors represents and warrants to Administrative Agent, Issuing Bank and
Lenders, with full knowledge that

                                       10
<PAGE>

Administrative Agent, Issuing Bank, and Lenders are relying on the following
representations and warranties in executing this Amendment, as follows:

      (a) each Obligor has the organizational power and authority to execute,
deliver and perform this Amendment and such other Loan Documents executed in
connection herewith, and all organizational action on the part of such Person
requisite for the due execution, delivery and performance of this Amendment and
such other Loan Documents executed in connection herewith has been duly and
effectively taken;

      (b) the Credit Agreement, as amended by this Amendment, the Loan Documents
and each and every other document executed and delivered in connection with this
Amendment to which any Obligor is a party constitute the legal, valid and
binding obligations of each Obligor to the extent it is a party thereto,
enforceable against such Person in accordance with their respective terms;

      (c) this Amendment does not and will not violate any provisions of any of
the organizational documents of any Obligor, or any contract, agreement,
instrument or requirement of any Governmental Authority to which any Obligor is
subject. Obligors' execution of this Amendment will not result in the creation
or imposition of any lien upon any properties of any Obligor, other than those
permitted by the Credit Agreement and this Amendment;

      (d) the execution, delivery and performance of this Amendment by Obligors
does not require the consent or approval of any other Person, including, without
limitation, any regulatory authority or governmental body of the United States
of America or any state thereof or any political subdivision of the United
States of America or any state thereof; and

      (e) no Default exists, and all of the representations and warranties
contained in the Credit Agreement and all instruments and documents executed
pursuant thereto or contemplated thereby are true and correct in all material
respects on and as of this date, other than those which have been disclosed to
Administrative Agent, Issuing Bank and Lenders in writing.

      SECTION 5. REFERENCE TO AND EFFECT ON THE AGREEMENT.

      (a) On and after the Amendment Effective Date, each reference in the
Credit Agreement to "this Agreement," "hereunder," "hereof," "herein," or words
of like import shall mean and be a reference to the Credit Agreement, as amended
hereby.

      (b) Except as otherwise expressly provided herein, the Credit Agreement
and the other Loan Documents are not amended, modified or affected by this
Amendment. Obligors ratify and confirm that (a) except as expressly amended
hereby, all of the terms, conditions, covenants, representations, warranties and
all other provisions of the Credit Agreement remain in full force and effect,
(b) each of the other Loan Documents are and remain in full force and effect in
accordance with their respective terms, and (c) the collateral under the
Security Instruments is unimpaired by this Amendment.

      SECTION 6. COSTS, EXPENSES AND TAXES. Borrower agrees to pay on demand all
reasonable costs and expenses of Administrative Agent in connection with the
preparation, reproduction, execution and delivery of this Amendment, and the
other instruments and documents to be delivered hereunder, including reasonable
attorneys' fees and out-of-pocket expenses of Administrative Agent. In addition,
Borrower shall pay any and all recording and filing fees payable or determined
to be payable in connection with the execution and delivery, filing or recording
of this Amendment and the other instruments and documents to be delivered
hereunder, and agrees to save Administrative Agent harmless

                                       11
<PAGE>

from and against any and all liabilities with respect to or resulting from any
delay in paying or omission to pay such taxes or fees.

      SECTION 7. DISCLOSURE OF CLAIMS. As additional consideration to the
execution, delivery, and performance of this Amendment by the parties hereto and
in order to induce Administrative Agent, Issuing Bank and Lenders to enter into
this Amendment, each Obligor represents and warrants that it knows of no
defenses, counterclaims or rights of setoff to the payment of any Indebtedness.

      SECTION 8. AFFIRMATION OF GUARANTY AGREEMENTS, SECURITY INTEREST.

      (a) Each of the undersigned Guarantors hereby consents to and accepts the
terms and conditions of this Amendment, and the transactions contemplated
hereby, agrees to be bound by the terms and conditions hereof, and ratifies and
confirms that each Guaranty Agreement and each of the other Loan Documents to
which it is a party is, and shall remain, in full force and effect after giving
effect to this Amendment.

      (b) Obligors hereby confirm and agree that any and all liens, security
interest and other security or collateral now or hereafter held by
Administrative Agent for the benefit of Lenders as security for payment and
performance of the Obligations hereby under such Security Instruments to which
such Obligor is a party are renewed and carried forth to secure payment and
performance of all of the Obligations. The Security Instruments are and remain
legal, valid and binding obligations of the parties thereto, enforceable in
accordance with their respective terms.

      SECTION 9. EXISTING REVOLVER LOANS AND LETTERS OF CREDIT The Register
located at the Principal Office of the Administrative Agent is hereby updated to
reflect the revised Revolver Commitments of the Revolver Lenders. In connection
therewith, Borrower, the Administrative Agent, and the Lenders shall make
adjustments to (i) the outstanding principal amount of the Revolver Loans (but
not any interest accrued thereon prior to the Amendment Effective Date or any
accrued commitment fees under the Credit Agreement prior to the Amendment
Effective Date), including the borrowing of additional Revolver Loans (which may
include LIBOR Loans) and the repayment of Revolver Loans (which may include the
prepayment or conversion of LIBOR Loans) plus all applicable accrued interest,
fees and expenses as shall be necessary to provide for Revolver Loans by each
Revolver Lender in the amount of its new Percentage Share of all Revolver Loans
as of the Amendment Effective Date, and (ii) participations in outstanding
Letters of Credit as of the Amendment Effective Date to provide for each
Revolver Lender's participation in each outstanding Letter of Credit as of the
Amendment Effective Date equal to such Revolver Lender's new Percentage Share of
the aggregate amount available to be drawn under each such Letter of Credit as
of the Amendment Effective Date. In connection with the foregoing, each Revolver
Lender shall be deemed to have made an assignment of its outstanding Revolver
Loans and Revolver Commitments under the Credit Agreement, and assumed
outstanding Revolver Loans and Revolver Commitments of other Revolver Lenders
under the Credit Agreement, all at the request of the Borrower, as may be
necessary to effect the foregoing, and each such Lender shall be entitled to any
reimbursement under Section 5.05 of the Credit Agreement in respect thereof.

      SECTION 10. EXECUTION AND COUNTERPARTS. This Amendment may be executed in
any number of counterparts and by different parties hereto in separate
counterparts, each of which when so executed and delivered shall be deemed to be
an original and all of which taken together shall constitute but one and the
same instrument. Delivery of an executed counterpart of this Amendment by
facsimile and other Loan Documents shall be equally as effective as delivery of
a manually executed counterpart of this Amendment and such other Loan Documents.

                                       12
<PAGE>

      SECTION 11. GOVERNING LAW. This Amendment shall be governed by and
construed in accordance with the laws of the State of New York.

      SECTION 12. HEADINGS. Section headings in this Amendment are included
herein for convenience and reference only and shall not constitute a
part of this Amendment for any other purpose.

      SECTION 13. NO ORAL AGREEMENTS. THE CREDIT AGREEMENT (AS AMENDED BY THIS
AMENDMENT) AND THE OTHER LOAN DOCUMENTS REPRESENT THE FINAL AGREEMENT BETWEEN
THE PARTIES AND MAY NOT BE CONTRADICTED BY EVIDENCE OF PRIOR, CONTEMPORANEOUS OR
SUBSEQUENT ORAL AGREEMENTS OF THE PARTIES.

      THERE ARE NO UNWRITTEN ORAL AGREEMENTS BETWEEN THE PARTIES.

            [THE REMAINDER OF THIS PAGE INTENTIONALLY BLANK. SIGNATURE PAGES TO
      FOLLOW.]

                                       13
<PAGE>

      IN WITNESS WHEREOF, the parties have executed this First Amendment to
Credit Agreement as of the day and year first above written.

                           BORROWER:

                           ATLAS PIPELINE PARTNERS, L.P.,
                           a Delaware limited partnership

                           By: Atlas Pipeline Partners GP, LLC,
                               its general partner

                               By: _____________________________________
                                   Michael L. Staines
                                   President and Chief Operating Officer

                           GUARANTORS:

                           ATLAS PIPELINE NEW YORK, LLC,
                           a Pennsylvania limited liability company

                           By: Atlas Pipeline Operating Partnership, L.P.,
                               a Delaware limited partnership
                               and its sole member

                               By: Atlas Pipeline Partners GP, LLC,
                                   a Delaware limited liability company
                                   and its sole general partner

                                   By: _____________________________________
                                       Michael L. Staines
                                       President and Chief Operating Officer

                           ATLAS PIPELINE OHIO, LLC,
                           a Pennsylvania limited liability company

                           By: Atlas Pipeline Operating Partnership, L.P.,
                               a Delaware limited partnership
                               and its sole member

                               By:  Atlas Pipeline Partners GP, LLC,
                                    a Delaware limited liability company
                                    and its sole general partner

                                    By: _____________________________________
                                        Michael L. Staines
                                        President and Chief Operating Officer

                                SIGNATURE PAGE TO
                       FIRST AMENDMENT TO REVOLVING CREDIT
                             AND TERM LOAN AGREEMENT

<PAGE>

                           ATLAS PIPELINE PENNSYLVANIA, LLC,
                           a Pennsylvania limited liability company

                           By: Atlas Pipeline Operating Partnership, L.P.,
                               a Delaware limited partnership
                               and its sole member

                               By:  Atlas Pipeline Partners GP, LLC,
                                    a Delaware limited liability company
                                    and its sole general partner

                                    By:_____________________________________
                                       Michael L. Staines
                                       President and Chief Operating Officer

                           ATLAS PIPELINE OPERATING PARTNERSHIP, L.P.,
                           a Delaware limited partnership

                           By:  Atlas Pipeline Partners GP, LLC,
                                a Delaware limited liability company
                                and its sole general partner

                                   By:_____________________________________
                                      Michael L. Staines
                                      President and Chief Operating Officer

                           ATLAS PIPELINE MID-CONTINENT LLC,
                           a Delaware limited liability company

                           By: Atlas Pipeline Operating Partnership, L.P.,
                               a Delaware limited partnership
                               and its sole member

                               By: Atlas Pipeline Partners GP, LLC,
                                   a Delaware limited liability company
                                   and its sole general partner

                                   By:_____________________________________
                                      Michael L. Staines
                                      President and Chief Operating Officer

                               SIGNATURE PAGE TO
                       FIRST AMENDMENT TO REVOLVING CREDIT
                             AND TERM LOAN AGREEMENT

<PAGE>

                        ELK CITY OKLAHOMA PIPELINE, L.P.,
                        a Texas limited partnership

                        By: Elk City Oklahoma GP, LLC,
                            a Delaware limited liability company
                            and its sole general partner

                            By: Atlas Pipeline Mid-Continent LLC,
                                a Delaware limited liability company
                                and its sole member

                                By: Atlas Pipeline Operating Partnership, L.P.,
                                    a Delaware limited partnership
                                    and its sole member

                                    By: Atlas Pipeline Partners GP, LLC,
                                        a Delaware limited liability company
                                        and its sole general partner

                                        By:_____________________________________
                                           Michael L. Staines
                                           President and Chief Operating Officer

                           ELK CITY OKLAHOMA GP, LLC,
                           a Delaware limited liability company

                           By: Atlas Pipeline Mid-Continent LLC,
                               a Delaware limited liability company
                               and its sole member

                               By: Atlas Pipeline Operating Partnership, L.P.,
                                   a Delaware limited partnership
                                   and its sole member

                                   By: Atlas Pipeline Partners GP, LLC,
                                       a Delaware limited liability company
                                       and its sole general partner

                                       By:_____________________________________
                                          Michael L. Staines
                                          President and Chief Operating Officer

                                SIGNATURE PAGE TO
                       FIRST AMENDMENT TO REVOLVING CREDIT
                             AND TERM LOAN AGREEMENT

<PAGE>

                           ATLAS ARKANSAS PIPELINE LLC,
                           an Oklahoma limited liability company

                           By: Atlas Pipeline Mid-Continent LLC,
                               a Delaware limited liability company
                               and its sole member

                               By: Atlas Pipeline Operating Partnership, L.P.,
                                   a Delaware limited partnership
                                   and its sole member

                                   By: Atlas Pipeline Partners GP, LLC,
                                       a Delaware limited liability company
                                       and its sole general partner

                                       By:_____________________________________
                                          Michael L. Staines
                                          President and Chief Operating Officer

                                SIGNATURE PAGE TO
                       FIRST AMENDMENT TO REVOLVING CREDIT
                             AND TERM LOAN AGREEMENT

<PAGE>

                           ADMINISTRATIVE AGENT, ISSUING BANK
                           AND A LENDER:

                           WACHOVIA BANK, NATIONAL ASSOCIATION

                           By: _____________________________
                               Name: Jay Buckman
                               Title: Vice President

                                SIGNATURE PAGE TO
                       FIRST AMENDMENT TO REVOLVING CREDIT
                             AND TERM LOAN AGREEMENT

<PAGE>

                           LENDERS:

                           BANK OF AMERICA, N.A.

                           By: _________________________
                                   Name:
                                   Title:

                           BANK OF OKLAHOMA N.A.

                           By: _________________________
                                   Name:
                                   Title:

                           KEYBANK NATIONAL ASSOCIATION

                           By: _________________________
                                   Name:
                                   Title:

                           WELLS FARGO BANK, N.A.

                           By: _________________________
                                   Name:
                                   Title:

                           BNP PARIBAS

                           By: _________________________
                                   Name:
                                   Title:

                           NEWCOURT CAPITAL USA INC.

                           By: _________________________
                                   Name:
                                   Title:

                           COMERICA BANK

                                SIGNATURE PAGE TO
                       FIRST AMENDMENT TO REVOLVING CREDIT
                             AND TERM LOAN AGREEMENT

<PAGE>

                           By: _________________________
                                   Name:
                                   Title:

                           COMPASS BANK

                           By: _________________________
                                   Name:
                                   Title:

                           CITIBANK TEXAS, N.A.

                           By: _________________________
                                   Name:
                                   Title:

                           FORTIS CAPITAL CORP.

                           By: _________________________
                                   Name:
                                   Title:

                           GUARANTY BANK

                           By: _________________________
                                   Name:
                                   Title:

                           NATIONAL CITY BANK

                           By: _________________________
                                   Name:
                                   Title:

                           NATEXIS BANQUES POPULAIRES

                           By: _________________________
                                   Name:
                                   Title:

                                SIGNATURE PAGE TO
                       FIRST AMENDMENT TO REVOLVING CREDIT
                             AND TERM LOAN AGREEMENT

<PAGE>

                           UFJ BANK LIMITED, NEW YORK BRANCH

                           By: _________________________
                                   Name:
                                   Title:

                           WESTLB AG, NEW YORK BRANCH

                           By: _________________________
                                   Name:
                                   Title:

                           By: _________________________
                                   Name:
                                   Title:

                                SIGNATURE PAGE TO
                       FIRST AMENDMENT TO REVOLVING CREDIT
                             AND TERM LOAN AGREEMENT

<PAGE>

                                   SCHEDULE 1

                              Security Instruments

1.    First Amendment to Deed of Trust, Mortgage, Security Agreement and
      Financing Statement, dated October 31, 2005, from Atlas Pipeline
      Mid-Continent LLC to Wachovia Bank, National Association, Administrative
      Agent.

2.    First Amendment to Open-End Mortgage, Security Agreement and Financing
      Statement, dated October 31, 2005, from Atlas Pipeline New York, LLC to
      Wachovia Bank, National Association, Administrative Agent.

3.    First Amendment to Open-End Mortgage, Security Agreement and Financing
      Statement, dated October 31, 2005, from Atlas Pipeline Ohio, LLC to
      Wachovia Bank, National Association, Administrative Agent.

4.    First Amendment to Open-End Mortgage, Security Agreement and Financing
      Statement, dated October 31, 2005, from Atlas Pipeline Pennsylvania, LLC
      to Wachovia Bank, National Association, Administrative Agent.

5.    Pledge, Assignment and Security Agreement dated October 31, 2005, from
      Atlas Arkansas to Wachovia Bank, National Association, as Administrative
      Agent.