<PAGE>
                                                                     EXHIBIT 4.9

                                 AMENDMENT NO. 2
               TO AMENDED AND RESTATED INVESTORS' RIGHTS AGREEMENT

         THIS AMENDMENT NO. 2 TO AMENDED AND RESTATED INVESTORS' RIGHTS
AGREEMENT ("Amendment") is made and entered into as of April 1, 2002, by and
among SYMBION, INC., a Tennessee corporation formerly named "UniPhy Healthcare,
Inc." (the "Company"), J.H. WHITNEY III, L.P. ("JHW III"), J.H. WHITNEY IV, L.P.
("JHW IV"), WHITNEY STRATEGIC PARTNERS III, L.P. ("WSP" and together with JHW
III and JHW IV, the "Whitney Shareholders"), those persons holding five percent
(5%) or more of the outstanding capital stock of Physicians Surgical Care, Inc.,
a Delaware corporation ("PSC"), immediately prior to the closing of the Merger
(defined herein) as identified on Exhibit A attached hereto (the "PSC
Shareholders") and the other persons identified on Exhibit A (collectively, the
"Original Investors" and each individually, an "Original Investor"). The Whitney
Shareholders, the PSC Shareholders and the Original Investors are referred to
herein collectively as the "Investors."

                                R E C I T A L S:

         WHEREAS, the Company and the Original Investors are parties to that
certain Amended and Restated Investors' Rights Agreement, dated as of June 25,
1999 as amended by the Amendment No. 1 to Amended and Restated Investors' Rights
Agreement, dated as of August 11, 1999 (the "Investors' Rights Agreement");

         WHEREAS, the Company, PSC and Symbion Acquisition Sub, Inc. ("SAS") are
parties to that certain Agreement and Plan of Merger, dated as of March 7, 2002
(the "Merger Agreement") which provides, among other things, for SAS to be
merged with and into PSC (the "Merger");

         WHEREAS, it is a condition of PSC's obligations under the Merger
Agreement that the Company and the Original Investors amend the Investors'
Rights Agreement to add the Whitney Shareholders as parties thereto and to
provide the Whitney Shareholders with rights and obligations that are pari passu
with those of the ARC Key Shareholders and the UniPhy Preferred Shareholders as
well as all of the other rights of the Investors and the Anti-Dilution Investors
thereunder and to provide to the PSC Shareholders the rights and obligations of
an "Investor" solely for the purposes of Sections 2.3, 2.5, 2.6, 2.7, 2.8; 2.9,
2.10, 2.11, 2.12, 2.13, 2.14 and 3.1(b) of the Investors' Rights Agreement;

         WHEREAS, the Company and the Investors desire to amend the Investors'
Rights Agreement as set forth in this Amendment, pursuant to Section 6.5 of the
Investors' Rights Agreement; and

         NOW, THEREFORE, in consideration of the foregoing and the respective
covenants and agreements contained herein, the sufficiency of which is hereby
acknowledged, the parties hereby agree and consent to the following:


<PAGE>

1.       Definitions.

         (a)      Capitalized terms used herein without definition shall have
the same meanings ascribed to such terms in the Investors' Rights Agreement.

         (b)      The Investors' Rights Agreement is hereby amended by adding
the following as part of Section 1 in appropriate alphabetical order:

                  "Affiliate" shall mean (i) in the case of an entity, any
         Person who or which, directly or indirectly, through one or more
         intermediaries, controls or is controlled by, or is under common
         control with, any specified Person or (ii) in the case of an
         individual, such individual's spouse, children, grandchildren or
         parents or a trust primarily for the benefit of any of the foregoing.

                  "Preferred Stock" means the Series A Preferred Stock and the
         Series B Preferred Stock.

                  "Series A Preferred Stock" means the Series A Convertible
         Preferred Stock, par value $.01 per share, of the Company.

                  "Series B Preferred Stock" means the Series B Convertible
         Preferred Stock, par value $.01 per share, of the Company.

         (c)      The definition of "Registerable Securities" contained in
Section 1.1 of the Investors' Rights Agreement is hereby deleted in its entirety
and the following is hereby substituted therefor for all purposes:

                  "Registerable Securities" means (i) any and all shares of
         Common Stock of the Company held by the Investors or issued or issuable
         upon conversion of shares of Preferred Stock and any shares of Common
         Stock issued or issuable upon conversion of any shares of preferred
         stock; (ii) any other shares of Common Stock acquired or owned by any
         of the Investors prior to the Initial Offering if such Investor is an
         Affiliate of the Company; (iii) any Common Stock of the Company issued
         as (or issuable upon the conversion or exercise of any warrant, right
         or other security which is issued as) a dividend or other distribution
         with respect to, or in exchange for or in replacement of, such
         above-described securities; and (iv) any Common Stock of the Company
         issued upon conversion of any warrant, right or other security held by
         the Investors.

2.       Restrictions on Transfer. The Investors' Rights Agreement is hereby
further amended by adding and appending the following sentence at the end of
Section 2.1(b):

                  In addition, notwithstanding the provisions of paragraphs
         (a)(i) and (a)(ii) above, no such registration statement or opinion of
         counsel shall be necessary for a transfer by a Whitney Shareholder,
         UniPhy Preferred Shareholder or ARC Key Shareholder to any of its
         Affiliates if such transfer does not constitute a sale, provided the
         transferee will be subject to this Agreement to the same extent as if
         he were an original Investor hereunder.


                                       2
<PAGE>

3.       Demand Registration Rights. Section 2.2(a) of the Investors' Rights
Agreement is hereby deleted in its entirety and the following is hereby
substituted therefor for all purposes:

                  (a)      Subject to the conditions of this Section 2.2, if the
         Company shall receive at any time a written request from any UniPhy
         Preferred Shareholders, ARC Key Shareholders or Whitney Shareholders
         (for purposes of this Section 2.2, the "Demand Registration Investors")
         holding ten percent (10%) or more of the Registrable Securities then
         outstanding which are held by the Demand Registration Investors (the
         "Initiating Investors") that the Company file a registration statement
         under the Securities Act covering the registration of the Registrable
         Securities having an aggregate offering price to the public of not less
         than $1,000,000, then the Company shall, within thirty (30) days of the
         receipt thereof, give written notice of such request to all of the
         Demand Registration Investors, and subject to the limitations of this
         Section 2.2, use its best efforts to effect, as soon as practicable,
         the registration under the Securities Act of all Registrable Securities
         that the Demand Registration Investors request to be registered.

4.        Piggyback Registration Rights.

                  (a)      Section 2.3(a)(i) of the Investor' Rights Agreement
         is hereby deleted in its entirety and the following is hereby
         substituted therefor for all purposes:

                           (i)      In the case of the Initial Offering, no such
                  reduction shall reduce the securities being offered by the
                  Company for its own account to be included in the registration
                  and underwriting, and in no event shall the amount of
                  securities of the selling Investors included in the
                  registration be reduced below fifteen percent (15%) of the
                  total amount of securities included in such registration,
                  unless such offering is the Initial Offering and such
                  registration does not include shares of any other selling
                  shareholders, in which event any or all of the Registrable
                  Securities of the Investors may be excluded and in no event
                  will shares of any other selling shareholders be included in
                  such registration which would reduce the number of shares
                  which may be included by Investors without the written consent
                  of Investors holding not less than seventy-five percent (75%)
                  of the Registrable Securities held collectively by the UniPhy
                  Preferred Shareholders, the ARC Key Shareholders and the
                  Whitney Shareholders, and seventy-five (75%) of the
                  Registrable Securities by the UniPhy Founders proposed to be
                  sold in the offering.

                  (b)      Section 2.3(a)(ii) of the Investors' Rights Agreement
         is hereby deleted in its entirety and the following is hereby
         substituted therefor for all purposes:

                           (ii)     In the case of an underwritten primary
                  registration on behalf of the Company, the number of shares
                  that may be included in the underwriting shall be allocated,
                  first, to the Company; second to the UniPhy Preferred
                  Shareholders, the ARC Key Shareholders and the Whitney
                  Shareholders on a pro rata basis based on the total number of
                  Registrable Securities held by such UniPhy Preferred
                  Shareholders, ARC Key Shareholders and Whitney Shareholders;
                  third, to the UniPhy Founders on a pro rata basis based on the
                  total number of Registrable Securities held by the UniPhy
                  Founders; and fourth, to any shareholder of the Company (other
                  than an Investor) on a pro rata basis;


                                       3
<PAGE>

5.       Indemnification. The last proviso in Section 2.9(b) of the Investors'
Rights Agreement is hereby deleted in its entirety and the following is hereby
substituted therefor for all purposes:

                  provided further, that in no event shall any indemnity under
         this Section 2.9(b) exceed the proceeds from the offering received by
         such Investor.

6.       Assignment of Registration Rights. The term "affiliate" in Section 2.10
of the Investors' Rights Agreement is hereby deleted and the term "Affiliate" is
hereby substituted therefor for all purposes.

7.       Amendment of Registration Rights. The first sentence of Section 2.11 of
the Investors' Rights Agreement is hereby deleted in its entirety and the
following is hereby substituted therefor for all purposes:

                  Any provision of this Section 2 may be amended and the
         observance thereof may be waived (either generally or in a particular
         instance and either retroactively or prospectively), only with the
         written consent of the Company and the Investors owning at least
         two-thirds of the Registerable Securities then outstanding and, to the
         extent that any such amendment would adversely effect the UniPhy
         Founders, the written consent of the Investors' holding at least
         two-thirds of the Registerable Securities held by the UniPhy Founders;
         provided, however, that if any such amendment, waiver, discharge or
         termination shall in any way have an adverse or deleterious effect on
         the Whitney Shareholders, such amendment, waiver, discharge or
         termination shall require the Whitney Shareholders' prior written
         consent.

8.       Covenants of the Company. Section 3.1(c) of the Investors' Rights
Agreement is hereby deleted in its entirety and the following is hereby
substituted therefor for all purposes:

                  (c)      So long as a UniPhy Preferred Shareholder, ARC Key
         Shareholder (with its affiliates) or the Whitney Shareholders shall own
         not fewer than 110,000 shares of Registrable Securities (as adjusted
         for splits and combinations) (a "Major Investor") the Company will
         furnish each such Major Investor, as soon as practicable after the end
         of the first, second and third quarterly accounting periods in each
         fiscal year of the Company, and in any event within forty-five (45)
         days thereafter, a consolidated balance sheet of the Company as of the
         end of each such quarterly period, and a consolidated statement of
         income and a consolidated statement of cash flows of the Company for
         such period and for the current fiscal year to date, prepared in
         accordance with generally accepted accounting principles, with the
         exception that no notes need be attached to such statements and
         year-end audit adjustments may not have been made.


                                       4
<PAGE>

9.       Issuance of Additional Shares on Certain Dilutive Issues. The first
paragraph of Section 4.1 of the Investors' Rights Agreement is hereby deleted in
its entirety and the following is hereby substituted therefor for all purposes:

                  4.1.     Issuance of Additional Shares on Certain Dilutive
         Issues. In the event that, at any time prior to the closing of the
         Initial Offering, the consideration per share (determined pursuant to
         Section 4.1.4 below) for any Additional Share of Common Stock (as
         defined below) issued or deemed to be issued by the Company (the
         "Anti-Dilution Price") is less than the average price per share of the
         shares of Common Stock (or Preferred Stock that was converted to Common
         Stock) or Preferred Stock owned by each Investor identified on Exhibit
         A hereto as an anti-dilution Investor (the "Anti-Dilution Investors")
         at the time of the issuance giving rise to the issuance of additional
         shares pursuant to this Section 4.1 (the "Average Original Price"),
         then the Company shall issue to the Anti-Dilution Investors additional
         shares of Common Stock subject to the following provisions;

10.      Issuance of Additional Shares of Common Stock to Anti-Dilution
Investors upon Issuance of Additional Shares of Common Stock. Section 4.1.3 of
the Investors' Rights Agreement is hereby deleted in its entirety and the
following is hereby substituted therefor for all purposes:

                  4.1.3.   Issuance of Additional Shares of Common Stock to
         Anti-Dilution Investors Upon Issuance of Additional Shares of Common
         Stock. In the event that the Company at any time after the date hereof
         shall issue Additional Shares of Common Stock (including Additional
         Shares of Common Stock deemed to be issued pursuant to Subsection 4.1.2
         above), without consideration or for a consideration per share less
         than the Average Original Price, the Company shall issue to each
         Anti-Dilution Investor without further consideration, that number of
         Additional Shares of Common Stock equal to the result obtained by (a)
         dividing (i) the number of shares of Common Stock held by such
         Anti-Dilution Investor or Common Stock that an Anti-Dilution Investor
         could acquire upon conversion of any convertible preferred stock held
         by such Anti-Dilution Investor immediately prior to the issuance giving
         rise to the issuance of additional shares pursuant to this Section 4.1
         multiplied by its Average Original Price by (ii) the Anti-Dilution
         Price per share consideration received (or deemed to have been received
         pursuant to Section 4.1.2 above) by the Company for the Additional
         Shares of Common Stock and (b) subtracting from the quotient the number
         of shares of Common Stock held by each Anti-Dilution Investor and
         Common Stock that an Anti-Dilution Investor could acquire upon
         conversion of any convertible preferred stock held by such
         Anti-Dilution Investor immediately prior to the issuance giving rise to
         the issuance of additional shares pursuant to this Section 4.1.


                                       5
<PAGE>

11.      Rights of First Refusal. Section 4.2.1 of the Investors' Rights
Agreement is hereby deleted in its entirety and the following is hereby
substituted therefor for all purposes:

                  4.2.1    Subsequent Offerings. Each UniPhy Preferred
         Shareholder, ARC Key Shareholder and Whitney Shareholder (for purposes
         of this Section 4.2, the "First Refusal Investors") shall have a right
         of first refusal to purchase its pro rata share of all Equity
         Securities, as defined below, that the Company may, from time to time,
         propose to sell and issue after the date of this Amended and Restated
         Agreement, other than the Equity Securities excluded by Section 4.5
         hereof. Each First Refusal Investor's pro rata share is equal to the
         ratio of (A) the number of shares of the Company's Common Stock
         (assuming conversion of all Preferred Stock owned by such First Refusal
         Investor) of which such First Refusal Investor is deemed to be a holder
         immediately prior to the issuance of such Equity Securities to (B) the
         total number of shares of the Company's outstanding Common Stock
         (assuming conversion of all outstanding Preferred Stock) immediately
         prior to the issuance of the Equity Securities. The term "Equity
         Securities" shall mean (i) any Common Stock, preferred stock or other
         security of the Company, (ii) any security convertible, with or without
         consideration, into any Common Stock, preferred stock or other security
         (including any option to purchase such a convertible security), (iii)
         any security carrying any warrant or right to subscribe to or purchase
         any Common Stock, preferred stock or other security or (iv) any such
         warrant or right.

12.      Issuance of Equity Securities to Other Persons. The first sentence of
Section 4.2.3 is hereby deleted in its entirety and the following is hereby
substituted therefor for all purposes:

                  If not all of the First Refusal Investors elect to purchase
         their pro rata share of the Equity Securities then the Company shall
         promptly notify in writing the First Refusal Investors who do elect and
         shall offer such First Refusal Investors the right to acquire such
         unsubscribed shares.

13.      Amendment and Waiver. Section 6.5 of the Investors' Rights Agreement is
hereby deleted in its entirety and the following is hereby substituted therefor
for all purposes:

         6.5      Amendment and Waiver.

                  (a)      Except as otherwise expressly provided, this Amended
         and Restated Agreement may be amended or modified only upon the written
         consent of the Company and (i) the Investors holding at least
         seventy-five percent (75%) of the Registrable Securities held by the
         UniPhy Preferred Shareholders and the ARC Key Shareholders, (ii) the
         Investors holding at least seventy-five percent (75%) of the
         Registrable Securities held by the UniPhy Founders and (iii) the
         Investors holding at least seventy-five percent (75%) of the
         Registrable Securities held by the Whitney Shareholders; provided,
         however, (i) with respect to provisions of this Amended and Restated
         Agreement applicable only to the UniPhy Preferred Shareholders, the ARC
         Key Shareholders and the Whitney Shareholders, such provisions may be
         amended and modified solely upon the written consent of the Company and
         (x) the holders of at least seventy-five percent (75%) of the
         Registrable Securities held by the UniPhy Preferred Shareholders and
         the ARC Key Shareholders and (y) the holders of at least seventy-five
         percent (75%) of the Registrable Securities held by the Whitney


                                       6
<PAGE>

         Shareholders and (ii) with respect to provisions of this Amended and
         Restated Agreement applicable only to UniPhy Founders, such provisions
         may be amended and modified solely upon the written consent of the
         Company and the holders of at least seventy-five percent (75%) of the
         Registrable Securities held by the UniPhy Founders.

                  (b) Except as otherwise expressly provided, the obligations of
         the Company and the rights of the Investors under this Amended and
         Restated Agreement may be waived only with the written consent of (i)
         the Investors holding at least seventy-five percent (75%) of the
         Registrable Securities held by the UniPhy Preferred Shareholders and
         the ARC Key Shareholders, (ii) the Investors holding at least
         seventy-five percent (75%) of the Registrable Securities held by the
         UniPhy Founders and (iii) the Investors holding at least seventy-five
         percent (75%) of the Registrable Securities held by the Whitney
         Shareholders; provided, however, (i) with respect to the rights held
         only by the UniPhy Preferred Shareholders, the ARC Key Shareholders and
         the Whitney Shareholders, such rights may be waived solely upon the
         written consent of (x) the holders of at least seventy-five percent
         (75%) of the Registrable Securities held by the UniPhy Preferred
         Shareholders and the ARC Key Shareholders and (y) the holders of at
         least seventy-five percent (75%) of the Registrable Securities held by
         the Whitney Shareholders, and (ii) with respect to the rights held only
         by the UniPhy Founders, such rights may be waived solely upon the
         written consent of the holders of at least seventy-five percent (75%)
         of the Registrable Securities held by the UniPhy Founders.

14.      Whitney Amendment. The Investors' Rights Agreement is hereby amended by
adding and appending the following as Section 10 of the Investors' Rights
Agreement:

         10.      Addition of each of the Whitney Shareholders as a Party.
         Notwithstanding the provisions of Section 6.5 or any other Section
         hereof, upon the closing of the Merger:

                  (a)      Each of the Whitney Shareholders shall be a party to
         this Amended and Restated Agreement; and

                  (b)      Exhibit A attached to this Amended and Restated
         Agreement shall be amended to add each of the Whitney Shareholders as a
         person identified thereon, and each of the Whitney Shareholders shall
         be, and shall be included within the definition of, an "Investor" for
         purposes of this Amended and Restated Agreement; and

                  (c)      Exhibit A attached to this Amended and Restated
         Agreement shall be amended to identify each of the Whitney Shareholders
         as an "Anti-Dilution Investor," and each of the Whitney Shareholders
         shall be, and shall be included within the definition of, an
         "Anti-Dilution Investor" for purposes of this Amended and Restated
         Agreement; and

                  (d)      Exhibit A attached to this Amended and Restated
         Agreement shall be appended to identify each of JHW III, JHW IV and WSP
         as the "Whitney Shareholders," for purposes of this Amended and
         Restated Agreement; and


                                       7
<PAGE>

                  (e)      Whitney shall have, and be entitled and subject to,
         all of the rights, benefits, duties and obligations of an "Investor,"
         and an "Anti-Dilution Investor" under this Amended and Restated
         Agreement, subject to the terms hereof.

15.      Addition of the PSC Shareholders as Parties. The Investors' Rights
Agreement is hereby further amended by adding and appending the following as
Section 11, thereunder, of the Investors' Rights Agreement:

         11.      Addition of the PSC Shareholders as Parties. Notwithstanding
         the provisions of Section 6.5 or any other Section hereof, upon the
         closing of the Merger:

                  (a)      the PSC Shareholders shall be a party to this Amended
         and Restated Agreement; and

                  (b)      Exhibit A attached to this Amended and Restated
         Agreement shall be amended to add the PSC Shareholders as persons
         identified thereon, and the PSC Shareholders shall be, and shall be
         included within the definition of, an "Investor" solely for purposes
         Sections 2.3, 2.5, 2.6, 2.7, 2.8; 2.9, 2.10, 2.11, 2.12, 2.13, 2.14 and
         3.1(b) of this Amended and Restated Agreement; and

                  (c)      the PSC Shareholders shall have, and shall be
         entitled and subject to, all of the rights, benefits, duties and
         obligations of an "Investor" as provided only under Sections 2.3, 2.5,
         2.6, 2.7, 2.8; 2.9, 2.10, 2.11, 2.12, 2.13, 2.14 and 3.1(b) of this
         Amended and Restated Agreement, subject to the terms hereof.

16.      Notices. All notices to the Whitney Shareholders shall be delivered to
the following:

         c/o Whitney & Co.
         177 Broad Street
         Stamford, Connecticut  06901
         Attention:  Jeffrey R. Jay, M.D.

or such other address as the Whitney Shareholders may designate by ten (10) days
advance written notice to the other parties hereto.

17.      Requisite Approval. Upon execution and delivery of this Amendment by
the Company and Investors representing the requisite percentage of Registrable
Shares set forth in Section 6.5 of the Investors' Rights Agreement, this
Amendment shall constitute and be deemed to be an amendment to and part of the
Investors' Rights Agreement for all purposes.

18.      No Other Changes. Except as expressly set forth or contemplated in this
Amendment, the terms and conditions of the Investors' Rights Agreement shall
remain in place and shall not be altered, amended or changed in any manner
whatsoever, except by any further amendment to the Investors' Rights Agreement
made in accordance with the terms of the Investors' Rights Agreement, as hereby
amended.

19.      Counterparts. This Amendment may be executed in any number of
counterparts and by the different parties hereto on separate counterparts, each
of which when executed


                                       8
<PAGE>

and delivered shall be deemed an original effective for binding the parties
hereto, but all of which shall together constitute one and the same instrument.

20.      Governing Law. This Amendment shall be governed by and construed in
accordance with the laws of the State of California, without regard to the
principles of conflicts of law thereof.


                                       9
<PAGE>

         IN WITNESS WHEREOF, the parties hereto have executed this Amendment No.
2 to the Amended and Restated Investors' Rights Agreement, and hereby consent to
the amendment and modification of the Investors' Rights Agreement provided
herein, as of the date first above written.

THE COMPANY:

SYMBION, INC.



By: /s/ Richard E. Francis, Jr.
    ----------------------------------------
Name: Richard E. Francis, Jr.
      --------------------------------------
Title: President and Chief Executive Officer
       -------------------------------------


INVESTORS:

UNIPHY PREFERRED SHAREHOLDERS:

ABS Capital Partners, L.P.



By: /s/ Frederick L. Bryant
    ----------------------------------------
Name: Frederick L. Bryant
     ---------------------------------------
Title:
       -------------------------------------



/s/ Clifford G. Adlerz
--------------------------------------------
Clifford G. Adlerz



--------------------------------------------
Randy W. Cook



--------------------------------------------
Paul Davis



/s/ Richard E. Francis, Jr.
--------------------------------------------
Richard E. Francis, Jr.



/s/ R. Dale Kennedy
--------------------------------------------
R. Dale Kennedy


                                       10
<PAGE>

--------------------------------------------
Tod Lambert

THE MARTIN COMPANIES, INC.



By: /s/ Charles N. Martin
    ----------------------------------------
Name: Charles N. Martin
     ---------------------------------------
Title:
      --------------------------------------



/s/ Kenneth C. Mitchell
--------------------------------------------
Kenneth C. Mitchell


Pacific Venture Group, L.P.
By:      PVG Equity Partner, L.L.C.,
         its General Partner



/s/ Eve M. Kurtin
--------------------------------------------
By: Eve M. Kurtin
Title: Member


PVG Associates, L.P.
By:      PVG Equity Partner, L.L.C.,
         its General Partner



/s/ Eve M. Kurtin
--------------------------------------------
By: Eve M. Kurtin
Title: Member



/s/ Patrick R. Rooney
--------------------------------------------
Patrick R. Rooney



/s/ Teresa F. Sparks
--------------------------------------------
Teresa F. Sparks



/s/ Gregg Stanley
--------------------------------------------
Gregg Stanley



/s/ Anthony Taparo
--------------------------------------------
Anthony Taparo


                                       11
<PAGE>

ARC KEY SHAREHOLDERS:

ARTHUR S. DEMOSS FOUNDATION


By:
    ----------------------------------------
Name:
     ---------------------------------------
Title:
      --------------------------------------



/s/ Jerry M. Eyler
--------------------------------------------
Jerry M. Eyler


FIRST AVENUE PARTNERS, L.P.

By:
    ----------------------------------------
Name:
     ---------------------------------------
Title:
      --------------------------------------



--------------------------------------------
William H. Freeman



--------------------------------------------
J. Michael Gould


HEALTH TECH AFFILIATES, INC.

By:
    ----------------------------------------
Name:
     ---------------------------------------
Title:
      --------------------------------------


HLM/CB Fund, L.P.

By:
    ----------------------------------------
Name:
     ---------------------------------------
Title:
      --------------------------------------


HLM Partners VII, L.P.

By:
    ----------------------------------------
Name:
     ---------------------------------------
Title:
      --------------------------------------


                                       12
<PAGE>

--------------------------------------------
W. Lawrence Hough


Piper Jaffray, Inc.

By:
    ----------------------------------------
Name:
     ---------------------------------------
Title:
      --------------------------------------



--------------------------------------------
B. Max Lauderdale


/s/ Charles N. Martin, Jr.
--------------------------------------------
Charles N. Martin, Jr.


/s/ Charles T. Neal
--------------------------------------------
Charles T. Neal



--------------------------------------------
Thomas Patten



--------------------------------------------
Keith B. Pitts



--------------------------------------------
Gary J. Prosterman


                                       13
<PAGE>

RICHLAND VENTURES II, L.P.



By:  /s/ Jack Tyrrell
     ---------------------------------------
Name:    Jack Tyrrell
Title:   Managing Partner

RICHLAND VENTURES III, L.P.



By:  /s/ Jack Tyrrell
     ---------------------------------------
Name:    Jack Tyrrell
Title:   Managing Partner



--------------------------------------------
Ann R. Schaaf


SOUTH ATLANTIC PRIVATE EQUITY FUND IV (QP),
LIMITED PARTNERSHIP

By: /s/ Donald W. Burton
    ----------------------------------------
Name: Donald W. Burton
     ---------------------------------------
Title: Managing Director
       -------------------------------------


SOUTH ATLANTIC PRIVATE EQUITY FUND IV, L.P.

By: /s/ Donald W. Burton
    ----------------------------------------
Name: Donald W. Burton
     ---------------------------------------
Title: Managing Director
       -------------------------------------



--------------------------------------------
Cal Turner, Jr.


/s/ William V.B. Webb
--------------------------------------------
William V.B. Webb

WW TWO, L.P.

By:
    ----------------------------------------
Name:
     ---------------------------------------
Title:
       -------------------------------------



--------------------------------------------
James A. Webb, III


                                       14
<PAGE>

WHITNEY SHAREHOLDERS:

J.H. WHITNEY III, L.P.

By:  J. H. Whitney Equity Partners III, L.L.C.,
         Its General Partner

By: /s/ Daniel J. O'Brien
    -------------------------------------------
Name: Daniel J. O'Brien
      -----------------------------------------
Title:   Managing Member
         --------------------------------------


J.H. WHITNEY IV, L.P.

By: J.H. Whitney Equity Partners IV, L.L.C.,
         Its General Partner

By:  /s/ Daniel J. O'Brien
     ------------------------------------------
Name: Daniel J. O'Brien
      -----------------------------------------
Title:   Managing Member
         --------------------------------------

WHITNEY STRATEGIC PARTNERS III, L.P.

By:  J. H. Whitney Equity Partners III, L.L.C.,
         Its General Partner

By:  /s/ Daniel J. O'Brien
     ------------------------------------------
Name: Daniel J. O'Brien
      -----------------------------------------
Title:   Managing Member
         --------------------------------------


UNIPHY FOUNDERS:



-----------------------------------------------
Peter Davidson



/s/ Shannon W. Fiser
-----------------------------------------------
Shannon W. Fiser


THE FRANCIS IRREVOCABLE TRUST, ANN FRANCIS,
TRUSTEE

By: /s/ Richard E. Francis, Jr.
    -------------------------------------------
Name: Richard E. Francis, Jr.
     ------------------------------------------
Title: Executor
       ----------------------------------------


                                       15
<PAGE>

--------------------------------------------
Victor Giovanetti


/s/ George M. Goodwin
--------------------------------------------
George M. Goodwin



--------------------------------------------
Marlene D. Kelley


/s/ H. Edward Kleine III
--------------------------------------------
H. Edward Kleine III


/s/ Darrell Naish
--------------------------------------------
Darrell Naish


/s/ Richard Panek
--------------------------------------------
Richard Panek


/s/ Vickie R. Warren
--------------------------------------------
Vickie R. Warren


PSC SHAREHOLDERS


/s/ Walter E. Schwing, Jr.
--------------------------------------------
Walter E. Schwing, Jr.


/s/ Robert Schwing
--------------------------------------------
Robert Schwing


                                       16
<PAGE>

ADDITIONAL UNIPHY PREFERRED SHAREHOLDERS:


--------------------------------------------
Bruce F. Chafin



--------------------------------------------
Ray Denson and Mary Denson, as joint tenants



--------------------------------------------
Ray Denson and Mary Denson, as Custodians
for Logan V. Denson



--------------------------------------------
Ray Denson and Mary Denson, as Custodians
for Morgan R. Denson



--------------------------------------------
Robert E. Galloway



--------------------------------------------
Stephen E. Hobbs



--------------------------------------------
Jeffrey W. Moore



--------------------------------------------
Joseph D. Moore



--------------------------------------------
Paul J. Moore



--------------------------------------------
Carol A. Murdock



--------------------------------------------
Phillip W. Roe


                                       17
<PAGE>

--------------------------------------------
Alan G. Thomas



--------------------------------------------
Daniel B. Soltman



--------------------------------------------
Ronald P. Soltman, as Custodian
for Sarah C. Soltman



--------------------------------------------
Ronald P. Soltman, as Custodian
for Joel M. Soltman


                                       18
<PAGE>

                                    EXHIBIT A

                              SCHEDULE OF INVESTORS

UNIPHY PREFERRED SHAREHOLDERS

ABS Capital Partners, L.P.*
Clifford G. Adlerz*
Bruce F. Chafin*
Randy W. Cook*
Paul Davis*
Ray Denson and Mary Denson, as joint tenants*
Ray Denson and Mary Denson, as Custodians for Logan V. Denson*
Ray Denson and Mary Denson, as Custodians for Morgan R. Denson*
Richard E. Francis, Jr.*
Robert E. Galloway*
Stephen E. Hobbs*
W. Lawrence Hough*
R. Dale Kennedy*
Tod Lambert
Kenneth C. Mitchell*
Jeffrey W. Moore*
Joseph D. Moore*
Paul J. Moore*
Carol A. Murdock*
Pacific Venture Group, L.P.*
Keith B. Pitts*
PVG Associates, L.P.*
Phillip W. Roe*
Patrick R. Rooney*
Teresa F. Sparks*
Gregg Stanley*
Anthony Taparo*
The Martin Companies, Inc.*
Alan G. Thomas*
Daniel B. Soltman*
Ronald P. Soltman, as Custodian for Sarah C. Soltman*
Ronald P. Soltman, as Custodian for Joel M. Soltman*
William V.B. Webb*

ARC KEY SHAREHOLDERS

Arthur S. Demoss Foundation*
Jerry M. Eyler*
First Avenue Partners, L.P.*
William H. Freeman
J. Michael Gould
Health Tech Affiliates, Inc.
HLM/CB Fund, L.P.*
HLM Partners VII, L.P.*
W. Lawrence Hough*

*   ANTI-DILUTION INVESTOR


                                       19
<PAGE>

Piper Jaffray, Inc.*
B. Max Lauderdale
Charles N. Martin, Jr.*
Charles T. Neal*
Thomas Patten
Keith B. Pitts*
Gary J. Prosterman
Richland Ventures II, L.P.*
Richland Ventures III, L.P.*
Ann R. Schaaf
South Atlantic Private Equity Fund IV (QP)*
South Atlantic Private Equity Fund
IV, L.P.*
Cal Turner, Jr.*
William V.B. Webb*
WW Two, L.P.*
James A. Webb, III


WHITNEY SHAREHOLDERS

J.H. Whitney III, L.P.*
J.H. Whitney IV, L.P.*
Whitney Strategic Partners III, L.P.*

UNIPHY FOUNDERS

Peter Davidson
Shannon W. Fiser
The Francis Irrevocable Trust, Ann Francis, Trustee*
Victor Giovanetti
George M. Goodwin
Marlene D. Kelley
H. Edward Kleine III
Darrell Naish
Richard Panek
Vickie R. Warren

PSC SHAREHOLDERS

Walter E. Schwing, Jr.
Robert Schwing




*  ANTI-DILUTION INVESTOR


                                       20