<PAGE>   1
                                                                   EXHIBIT 10.74





                               AMENDMENT NO. 1 TO
                  MASTER CONSTRUCTION LINE OF CREDIT AGREEMENT

         THIS AMENDMENT NO. 1 TO MASTER CONSTRUCTION LINE OF CREDIT
AGREEMENT, dated as of March 1, 2000 ("THIS AMENDMENT"), among the following:

                  (I) THIRD PARTY INVESTORS I, LLC, a Delaware limited liability
         company (herein, together with its successors and assigns, the
         "BORROWER");

                  (II) the lending institutions listed on the signature pages
         hereof (the "LENDERS");

                  (IV) FLEET NATIONAL BANK, a national banking association, and
         THE HUNTINGTON NATIONAL BANK, a national banking association, as
         Co-Agents; and

                  (V) KEY CORPORATE CAPITAL INC., a Michigan corporation, as
         administrative agent (the "ADMINISTRATIVE AGENT").

         PRELIMINARY STATEMENTS:

         (1) The parties hereto entered into the Master Construction Line of
Credit Agreement, dated as of August 31, 1999 (the "CREDIT AGREEMENT"; with the
terms defined therein, or the definitions of which are incorporated therein,
being used herein as so defined).

         (2) In connection with the execution and delivery of the Credit
Agreement, Alterra Healthcare Corporation, a Delaware corporation (herein,
together with its successors and assigns, the "COMPANY") and the Administrative
Agent entered into the Guaranty, dated as of August 31, 1999, as amended by
Amendment No. 1 thereto, dated as of the date hereof in the form attached hereto
as Exhibit A (as so amended, the "GUARANTY").

         (3) The parties hereto desire to change certain of the terms and
provisions of the Credit Agreement, all as more fully set forth below.

         NOW, THEREFORE, the parties hereby agree as follows:

         SECTION 1. AMENDMENTS, ETC.

         1.1. INTEREST. Effective on the Effective Date of this Amendment
provided for in section 4 hereof, sections 2.9 (a) and (b) of the Credit
Agreement are amended to read in their entirety as follows:

                  (A) INTEREST ON PRIME RATE LOANS. During any period in which a
         Loan is a Prime Rate Loan, the unpaid principal amount of such Loan
         shall bear interest at a fluctuating rate per annum which shall at all
         times be equal to the Prime Rate in effect from time to time, PROVIDED
         that during the Construction Period for such Project an interest rate
         margin of 25 basis points shall be added to such Prime Rate, PROVIDED
         FURTHER that if (A) the New Capital Commitment Requirement is satisfied
         by April 20, 2000, (B) the New Capital Funding Requirement is




<PAGE>   2
         satisfied by June 30, 2000, and (C) the Administrative Agent notifies
         the parties hereto that such conditions have been satisfied (which the
         Administrative Agent shall issue promptly upon satisfaction of such
         conditions), then on the effective date of such notice from the
         Administrative Agent, but not earlier than July 1, 2000, the interest
         rate margin specified in the foregoing clause shall change from 25
         basis points to zero basis points.

                  (B) INTEREST ON LIBOR LOANS. During any Interest Period for a
         LIBOR Loan for a Project, the unpaid principal amount of such Loan
         shall bear interest at a rate per annum which shall at all times be the
         relevant Adjusted LIBOR Rate for such Loan PLUS (i) during the
         Construction Period for such Project, the LIBOR Construction Period
         Margin; or (ii) during the Mini-Perm Period for such Project, the LIBOR
         Lease-Up Period Margin prior to the time Stabilization of such Project
         is achieved, or the LIBOR Stabilized Period Margin after Stabilization
         of such Project has been achieved. Notwithstanding the foregoing, no
         reduction in the interest rate margin pursuant to the preceding
         sentence shall be effective for any Loans for a Project until at least
         two Business Days after the Administrative Agent shall have received
         written notice from the Borrower of the occurrence of the event or
         circumstance giving rise to such reduction and referring specifically
         to the interest rate margin provisions of this section 2.9(b).

         1.2. EFFECTIVENESS OF PRICING CHANGES. The pricing changes effected
pursuant to section 1.1 of this Amendment shall be applicable as of and from and
after January 1, 2000, for all Loans outstanding on such date or thereafter.

         1.3. INTEREST PERIODS. Effective on the Effective Date of this
Amendment provided for in section 4 hereof, section 2.10(a) of the Credit
Agreement is amended to read in its entirety as follows:

                  2.10 INTEREST PERIODS. (a) During the Construction Period for
         a Project, subject to the conditions set forth herein, the Borrower
         shall have the right, upon not less than three Business Days' written
         notice to the Administrative Agent, to elect whether the Loans shall be
         Prime Rate Loans or LIBOR Rate Loans. Each Interest Period for any
         LIBOR Loan for such Project shall be the calendar month, and the
         Adjusted LIBOR Rate applicable to all LIBOR Loans for such Project
         which are outstanding during such Interest Period (whether previously
         incurred or incurred during such Interest Period) shall be determined
         prior to the commencement of such Interest Period in accordance with
         the definition of the term Adjusted LIBOR Rate. The initial Interest
         Period of the Construction Period for a Project for any LIBOR Rate
         Loans shall commence on the date such Construction Period commences or
         on such later date permitted hereunder if the Borrower initially elects
         Prime Rate Loans in accordance with the provisions set forth herein. In
         the event that the Borrower fails to elect a Type for the Loans in
         accordance with the provisions set forth herein, the Borrower shall be
         deemed to have selected LIBOR Rate Loans; provided, however, in no
         event shall LIBOR Rate Loans be permitted if the Interest Period would
         end after the expiration of the Construction Period for such Project.

         1.4. MONTHLY PROJECT FINANCIAL STATEMENTS. Effective on the Effective
Date of this Amendment provided for in section 4 hereof, section 8.1(d) of the
Credit Agreement is amended by deleting the text "within 45 days after the close
of each of the monthly accounting periods" and inserting in its place "within 60
days after the close of each of the monthly accounting periods".



                                        2

<PAGE>   3

         1.5. EVENTS OF DEFAULT. Effective on the Effective Date of this
Amendment provided for in section 4 hereof, sections 10.1(c), (e) and (j) of the
Credit Agreement respectively are amended to read in their entirety as follows:

                  (C) CERTAIN NEGATIVE COVENANTS: the Borrower shall default in
         the due performance or observance by it of any term, covenant or
         agreement contained in sections 9.1 through 9.8, inclusive, of this
         Agreement; or the Borrower shall default in the due performance or
         observance by it of any term, covenant or agreement contained in
         section 5, 10, 16(a)(i) or 16(c) of any Mortgage; or the Guarantor
         shall default in the due performance of any term, covenant or agreement
         contained in section 13(a), 13(b), 13(c), 13(d), 13(e), 13(h), 13(i),
         13(j) or 13(k) of the Alterra Guaranty; or

                  (E) CROSS DEFAULT: the Borrower, or the Guarantor or any of
         its Subsidiaries, shall (i) in the case of the Borrower, default in any
         payment with respect to any Indebtedness, other than the Obligations
         and any amounts owed by the Borrower to the Guarantor, and such default
         shall continue after the applicable grace period, if any, specified in
         the agreement or instrument relating to such Indebtedness, or (ii) in
         the case of the Guarantor or any of its Subsidiaries, default in any
         payment with respect to any Indebtedness owed to any Lender, or any
         other Indebtedness of $10,000,000 or greater, individually or in the
         aggregate, in each case other than the Obligations, and such default
         shall continue after the applicable grace period, if any, specified in
         the agreement or instrument relating to such Indebtedness and such
         default shall not have been cured or remedied prior to the acceleration
         of any of the Loans or other Obligations pursuant to section 10.2
         hereof, or (iii) default in the observance or performance of any
         agreement or condition relating to any such Indebtedness described in
         clause (i) or (ii) above or contained in any instrument or agreement
         evidencing, securing or relating thereto (and all grace periods
         applicable to such observance, performance or condition shall have
         expired and the existence thereof otherwise shall not have been
         eliminated by written amendment or waiver by the holder or holders of
         such Indebtedness (or a trustee or agent on behalf of such holder or
         holders) prior to the acceleration of any of the Loans or other
         Obligations pursuant to section 10.2 hereof ), or any other event shall
         occur or condition exist, the effect of which default or other event or
         condition is to cause, or to permit the holder or holders of such
         Indebtedness (or a trustee or agent on behalf of such holder or
         holders) to cause any such Indebtedness to become due prior to its
         stated maturity; or any such Indebtedness of the Borrower or of the
         Guarantor or any of its Subsidiaries shall be declared to be due and
         payable, or shall be required to be prepaid (other than by a regularly
         scheduled required prepayment or redemption, prior to the stated
         maturity thereof); or

                  (J) MATERIAL ADVERSE EFFECT, ETC.: (i) any event or
         circumstance shall occur or exist which has a Material Adverse Effect
         upon the Borrower or the Guarantor, as compared to the business,
         operations, property, assets, liabilities or condition (financial or
         otherwise) of the Borrower as reflected in the financial statements
         referred to in section 7.8, or the business, operations, property,
         assets, liabilities or condition (financial or otherwise) of the
         Guarantor and its Subsidiaries as reflected in the financial statements
         and the Financial Projections referred to in section 11(f) and 11(i) of
         the Alterra Guaranty, as applicable, other than changes in the
         condition of the Guarantor reflected in the Recent Financial
         Projections (as defined in the Guaranty); or

                  (ii) any representation or warranty contained in section 2.6
         of Amendment No. 1 to the Guaranty, dated as of March 1, 2000, with
         respect to the Recent Financial Projections


                                        3

<PAGE>   4

         referred to therein, shall prove to be untrue in any material respect
         as of the date when made or deemed made.

         1.6. ADDITIONAL DEFINITIONS. Effective on the Effective Date of this
Amendment provided for in section 4 hereof, the following definitions shall be
added to section 1.1 of the Credit Agreement in appropriate alphabetic order:

                  "EBITDAR COVERAGE REQUIREMENT" shall mean the requirement that
         the ratio of (i) Consolidated EBITDAR (as defined in the Guaranty) for
         any Testing Period (as defined in the Guaranty), to (ii) Consolidated
         Lease and Debt Service Charges (as defined in the Guaranty) for such
         Testing Period must equal or exceed 1.25 to 1.00, PROVIDED, the first
         eligible Testing Period to be measured hereunder shall be the fiscal
         quarter ending December 31, 2000.

                  "LIBOR CONSTRUCTION PERIOD MARGIN" shall mean (i) 250 basis
         points per annum, at all times during the period from the date of this
         Agreement through December 31, 1999, or (ii) 300 basis points per annum
         at all times thereafter, PROVIDED that if (A) the New Capital
         Commitment Requirement is satisfied by April 20, 2000, (B) the New
         Capital Funding Requirement is satisfied by June 30, 2000, and (C) the
         Administrative Agent notifies the parties hereto that such conditions
         have been satisfied (which the Administrative Agent shall issue
         promptly upon satisfaction of such conditions), then on the effective
         date of such notice from the Administrative Agent, but not earlier than
         July 1, 2000, the interest rate margin specified in clause (ii) above
         shall change from 300 basis points to 275 basis points, PROVIDED,
         FURTHER, that if (I) the interest rate margin had previously been
         reduced from 300 basis points to 275 basis points pursuant to the
         foregoing clause, (II) the EBITDAR Coverage Requirement is satisfied,
         and (III) the Administrative Agent notifies the parties hereto that
         such condition has been satisfied (which the Administrative Agent shall
         issue promptly upon satisfaction of such condition), then on the
         effective date of such notice from the Administrative Agent, the
         interest rate margin specified in clause (ii) above shall change from
         275 basis points to 250 basis points.

                  "LIBOR LEASE-UP PERIOD MARGIN" shall mean (i) 225 basis points
         per annum, at all times during the period from the date of this
         Agreement through December 31, 1999, or (ii) 275 basis points per annum
         at all times thereafter, PROVIDED that if (A) the New Capital
         Commitment Requirement is satisfied by April 20, 2000, (B) the New
         Capital Funding Requirement is satisfied by June 30, 2000, and (C) the
         Administrative Agent notifies the parties hereto that such conditions
         have been satisfied (which the Administrative Agent shall issue
         promptly upon satisfaction of such conditions), then on the effective
         date of such notice from the Administrative Agent, but not earlier than
         July 1, 2000, the interest rate margin specified in clause (ii) above
         shall change from 275 basis points to 250 basis points, PROVIDED,
         FURTHER, that if (I) the interest rate margin had previously been
         reduced from 275 basis points to 250 basis points pursuant to the
         foregoing clause, (II) the EBITDAR Coverage Requirement is satisfied,
         and (III) the Administrative Agent notifies the parties hereto that
         such condition has been satisfied (which the Administrative Agent shall
         issue promptly upon satisfaction of such condition), then on the
         effective date of such notice from the Administrative Agent, the
         interest rate margin specified in clause (ii) above shall change from
         250 basis points to 225 basis points.

                  "LIBOR STABILIZED PERIOD MARGIN" shall mean (i) 200 basis
         points per annum, at all times during the period from the date of this
         Agreement through December 31, 1999, or (ii) 250 basis points per annum
         at all times thereafter, PROVIDED that if (A) the New Capital
         Commitment Requirement is satisfied by April 20, 2000, (B) the New
         Capital Funding Requirement is satisfied by June 30, 2000, and (C) the
         Administrative Agent notifies the parties


                                        4

<PAGE>   5

         hereto that such conditions have been satisfied (which the
         Administrative Agent shall issue promptly upon satisfaction of such
         conditions), then on the effective date of such notice from the
         Administrative Agent, but not earlier than July 1, 2000, the interest
         rate margin specified in clause (ii) above shall change from 250 basis
         points to 225 basis points, PROVIDED, FURTHER, that if (I) the interest
         rate margin had previously been reduced from 250 basis points to 225
         basis points pursuant to the foregoing clause, (II) the EBITDAR
         Coverage Requirement is satisfied, and (III) the Administrative Agent
         notifies the parties hereto that such condition has been satisfied
         (which the Administrative Agent shall issue promptly upon satisfaction
         of such condition), then on the effective date of such notice from the
         Administrative Agent, the interest rate margin specified in clause (ii)
         above shall change from 225 basis points to 200 basis points.

         "NEW CAPITAL COMMITMENT REQUIREMENT" shall have the meaning provided in
section 13(i)(i) of the Guaranty.

         "NEW CAPITAL FUNDING REQUIREMENT" shall have the meaning provided in
section 13(i)(ii) of the Guaranty.

                  SECTION 2. REPRESENTATIONS AND WARRANTIES.

         The Borrower represents and warrants as follows:

         2.1. AUTHORIZATION AND VALIDITY OF AMENDMENT, ETC. This Amendment has
been duly authorized by all necessary corporate action on the part of the
Borrower, has been duly executed and delivered by a duly authorized officer of
the Borrower, and constitutes the valid and binding agreement of the Borrower,
enforceable against the Borrower in accordance with its terms, except to the
extent that the enforceability thereof may be limited by applicable bankruptcy,
insolvency, reorganization, moratorium or other similar laws generally affecting
creditors' rights and by equitable principles (regardless of whether enforcement
is sought in equity or at law).

         2.2. REPRESENTATIONS AND WARRANTIES. The representations and warranties
of the Credit Parties contained in the Credit Agreement, as amended hereby, or
in the other Credit Documents are true and correct in all material respects on
and as of the date hereof as though made on and as of the date hereof, except to
the extent that such representations and warranties expressly relate to an
earlier specified date, in which case such representations and warranties are
hereby reaffirmed as true and correct in all material respects as of the date
when made.

         2.3. NO EVENT OF DEFAULT. No condition or event has occurred or exists
which constitutes or which, after notice or lapse of time or both, would
constitute an Event of Default under the Credit Agreement as amended hereby,
under the Guaranty as amended or under the other Credit Documents.

         2.4. COMPLIANCE. The Borrower is in full compliance with all covenants
and agreements contained in the Credit Agreement, as amended hereby, and the
other Credit Documents to which it is a party.

         SECTION 3. RATIFICATIONS.

         Except as expressly modified and superseded by this Amendment, the
terms and provisions of the Credit Agreement are ratified and confirmed and
shall continue in full force and effect.



                                        5

<PAGE>   6

         SECTION 4. BINDING EFFECT.

         This Amendment shall become effective on a date (the "EFFECTIVE DATE"),
on or before March 24, 2000, if the following conditions shall have been
satisfied on and as of such date:

                  (A) EXECUTION OF AMENDMENT. This Amendment shall have been
         executed by the Borrower and the Administrative Agent, and counterparts
         hereof as so executed shall have been delivered to the Administrative
         Agent; and the Administrative Agent shall have been notified by the
         Required Lenders that such Lenders have executed this Amendment (which
         notification may be by facsimile or other written confirmation of such
         execution).

                  (B) GUARANTY. Amendment No. 1 to Guaranty shall have been
         executed by the Company and the Administrative Agent, and counterparts
         thereof as so executed shall have been delivered to the Administrative
         Agent.

                  (C) ACKNOWLEDGMENT AND CONSENT. The Acknowledgment and Consent
         appended hereto shall have been executed by the Company, and
         counterparts thereof as so executed shall have been delivered to the
         Administrative Agent.

                  (D) FEES. The Borrower or the Company shall have paid to the
         Administrative Agent, in immediately available funds, for the pro rata
         account of the Lenders who become a signatory hereto on or prior to the
         date established by the Administrative Agent, such nonrefundable
         amendment fees as have previously been agreed to by the Borrower and
         the Company and communicated to the Lenders (the Administrative Agent
         shall promptly distribute to such Lender its pro rata portion of such
         amendment fees).

Thereafter this Amendment shall be binding upon and inure to the benefit of the
Borrower, the Company, the Administrative Agent, and each Lender and their
respective permitted successors and assigns. After this Amendment becomes
effective, the Administrative Agent will promptly furnish a copy of this
Amendment and Amendment No. 1 to Guaranty to each Lender, the Borrower and the
Company and advise them of the Effective Date.

         SECTION 5. MISCELLANEOUS.

         5.1. SURVIVAL OF REPRESENTATIONS AND WARRANTIES. All representations
and warranties made in this Amendment shall survive the execution and delivery
of this Amendment, and no investigation by the Administrative Agent or any
Lender or any subsequent Loan shall affect the representations and warranties or
the right of the Administrative Agent or any Lender to rely upon them.

         5.2. REFERENCE TO CREDIT AGREEMENT. The Credit Agreement and any and
all other agreements, instruments or documentation now or hereafter executed and
delivered pursuant to the terms of the Credit Agreement as amended hereby, are
hereby amended so that any reference therein to the Credit Agreement shall mean
a reference to the Credit Agreement as amended hereby.

         5.3. EXPENSES. As provided in the Credit Agreement, but without
limiting any terms or provisions thereof, the Borrower or the Company shall pay
on demand all reasonable costs and expenses incurred by the Administrative Agent
in connection with the preparation, negotiation, and execution of this
Amendment, including without limitation the reasonable costs and fees of the


                                        6

<PAGE>   7

Administrative Agent's special legal counsel, regardless of whether this
Amendment becomes effective in accordance with the terms hereof, and all
reasonable costs and expenses incurred by the Administrative Agent or any Lender
in connection with the enforcement or preservation of any rights under the
Credit Agreement, as amended hereby.

         5.4. SEVERABILITY. Any term or provision of this Amendment held by a
court of competent jurisdiction to be invalid or unenforceable shall not impair
or invalidate the remainder of this Amendment and the effect thereof shall be
confined to the term or provision so held to be invalid or unenforceable.

         5.5. APPLICABLE LAW. This Amendment shall be governed by and construed
in accordance with the laws of the State of Ohio.

         5.6. HEADINGS. The headings, captions and arrangements used in this
Amendment are for convenience only and shall not affect the interpretation of
this Amendment.

         5.7. ENTIRE AGREEMENT. This Amendment is specifically limited to the
matters expressly set forth herein. This Amendment and all other instruments,
agreements and documentation executed and delivered in connection with this
Amendment embody the final, entire agreement among the parties hereto with
respect to the subject matter hereof and supersede any and all prior
commitments, agreements, representations and understandings, whether written or
oral, relating to the matters covered by this Amendment, and may not be
contradicted or varied by evidence of prior, contemporaneous or subsequent oral
agreements or discussions of the parties hereto. There are no oral agreements
among the parties hereto relating to the subject matter hereof or any other
subject matter relating to the Credit Agreement.

         5.8. JURY TRIAL WAIVER. EACH OF THE PARTIES TO THIS AMENDMENT HEREBY
IRREVOCABLY WAIVES ALL RIGHT TO A TRIAL BY JURY IN ANY ACTION, PROCEEDING OR
COUNTERCLAIM ARISING OUT OF OR RELATING TO THIS AMENDMENT, THE OTHER CREDIT
DOCUMENTS OR THE TRANSACTIONS CONTEMPLATED HEREBY OR THEREBY. EACH PARTY HERETO
HEREBY (A) CERTIFIES THAT NO REPRESENTATIVE, AGENT OR ATTORNEY OF ANY OTHER
PARTY HAS REPRESENTED, EXPRESSLY OR OTHERWISE, THAT SUCH OTHER PARTY WOULD NOT,
IN THE EVENT OF LITIGATION, SEEK TO ENFORCE THE FOREGOING WAIVER, AND (B)
ACKNOWLEDGES THAT IT AND THE OTHER PARTIES HERETO HAVE BEEN INDUCED TO ENTER
INTO THIS AMENDMENT BY, AMONG OTHER THINGS, THE MUTUAL WAIVERS AND
CERTIFICATIONS IN THIS SECTION.

         5.9. COUNTERPARTS. This Amendment may be executed by the parties hereto
separately in one or more counterparts, each of which when so executed shall be
deemed to be an original, but all of which when taken together shall constitute
one and the same agreement.



                                        7

<PAGE>   8

         IN WITNESS WHEREOF, this Amendment has been duly executed and delivered
as of the date first above written.



THIRD PARTY INVESTORS I, LLC

BY:  TWIN OAKS CAPITAL, LLC, ITS MANAGER


       BY:   /S/ RONALD G. KENNY
             ---------------------------
             PRESIDENT

KEY CORPORATE CAPITAL INC.,
     individually as a Lender and
     as Administrative Agent


BY:          /S/ DAVID A. MACVICAR
             ---------------------------
             VICE PRESIDENT

FLEET NATIONAL BANK,
     individually as a Lender and as Co-Agent


BY:         /S/ MARY SHEEHAN
            ----------------------------
            VICE PRESIDENT


THE HUNTINGTON NATIONAL BANK,
     individually as a Lender and as Co-Agent


BY:         /S/ GREGORY RANDALL
            ----------------------------
            VICE PRESIDENT




                                        8

<PAGE>   9

                           ACKNOWLEDGMENT AND CONSENT

         For the avoidance of doubt, and without limitation of the intent and
effect of sections 3 and 4 of the Guaranty executed and delivered by the
undersigned Company as guarantor (as each of such terms is defined in the Credit
Agreement referred to in the Amendment No. 1 to Credit Agreement (the
"AMENDMENT"), to which this Acknowledgment and Consent is appended), the
undersigned hereby unconditionally and irrevocably (i) acknowledges receipt of a
copy of the Credit Agreement and the Amendment, and (ii) consents to all of the
terms and provisions of the Credit Agreement as amended by the Amendment.

         Capitalized terms which are used herein without definition shall have
the respective meanings ascribed thereto in the Credit Agreement referred to
herein. This Acknowledgment and Consent is for the benefit of the Lenders and
the Administrative Agent, and their respective successors and assigns. No term
or provision of this Acknowledgment and Consent may be modified or otherwise
changed without the prior written consent of the Administrative Agent, given as
provided in the Credit Agreement. This Acknowledgment and Consent shall be
binding upon the successors and assigns of the undersigned.

         IN WITNESS WHEREOF, the undersigned has duly executed and delivered
this Acknowledgment and Consent as of the date of the Amendment referred to
herein.



                                 ALTERRA HEALTHCARE CORPORATION
                                       AS THE GUARANTOR


                                 BY:      /S/ MARK W. OHLENDORF
                                    -------------------------------------------
                                           SENIOR VICE PRESIDENT




                                        9