EXHIBIT (b)(2) August 24, 2001 Van Kampen Prime Rate Income Trust Van Kampen Senior Floating Rate Fund One Parkview Plaza Oakbrook Terrace, Illinois 60181 Ladies and Gentlemen: You and we are parties to that certain Credit Agreement dated as of April 17, 1997 and amended and restated pursuant to a Third Amendment of Credit Agreement dated as of September 13, 2000 (the "Credit Agreement"). Terms used herein shall, unless otherwise defined herein or the context otherwise requires, have the meanings assigned to such terms in the Credit Agreement as amended hereby. You and we have agreed that, effective as of the date of this letter agreement, the date September 12, 2001 appearing in clause (a) of the definition of the term Commitment Termination Date set forth in Schedule 1 of the Credit Agreement shall be amended to read November 9, 2001. The agreement of the Banks and the Agent to make such amendment is conditioned on the following (1) your execution of 12 counterparts of this letter agreement and delivery of such counterparts to the Agent no later than 10:00 a.m. (Central time) on September 5, 2001; and (2) that (i) no Default shall have occurred and be continuing as of the date upon which you shall be deemed to have executed this letter agreement, such execution to be deemed to be a certification by each of you to that effect and to the effect that each representation and warranty of each of you set forth in Article 5 of the Credit Agreement, as amended hereby, is true and correct as of the date hereof as though made on and as of such date, and (ii) each of you shall have furnished the Agent and the Banks such further documents as may be reasonably requested by the Agent and/or the Banks through the Agent. The Credit Agreement as amended hereby shall remain in full force and effect and is hereby ratified, adopted and confirmed in all respects. All references to the Credit Agreement in any other agreement or document shall hereafter be deemed to refer to the Credit Agreement as amended hereby. In addition, each reference in the Credit Agreement to the terms "this Agreement," "hereunder," "hereof" or terms or words of similar import shall hereafter mean the Credit Agreement as amended hereby. Van Kampen Prime Rate Income Trust Van Kampen Senior Floating Rate Fund August 24, 2001 Page 2 Please indicate your acceptance of the foregoing terms and conditions by signing the enclosed 12 counterpart copies of your signature page to this letter agreement and returning them to the Agent. Very truly yours, BANK OF AMERICA, N.A., as Agent and as a Bank By: /s/ Elizabeth Bishop ------------------------------------------- Title: Principal ---------------------------------------- THE BANK OF NEW YORK By: /s/ Patrick W. Miller ------------------------------------------- Title: Vice President ---------------------------------------- FLEET NATIONAL BANK By: /s/ Kenneth G. Ahrens ------------------------------------------- Title: Managing Director ---------------------------------------- STATE STREET BANK AND TRUST COMPANY By: /s/ Steven G. Carson ------------------------------------------- Title: Vice President ---------------------------------------- Van Kampen Prime Rate Income Trust Van Kampen Senior Floating Rate Fund August 24, 2001 Page 3 CITIBANK, N.A. By: /s/ Pierre Guigui ------------------------------------------- Title: Director ---------------------------------------- COMMERZBANK AKTIENGESELLSCHAFT, NEW YORK AND GRAND CAYMAN BRANCHES By: /s/ Sean Harrigan ------------------------------------------- Title: Senior Vice President ---------------------------------------- By: /s/ Robert Taylor ------------------------------------------- Title: Senior Vice President ---------------------------------------- CREDIT LYONNAIS NEW YORK BRANCH By: /s/ Sebastian Rocco ------------------------------------------- Title: Senior Vice President ---------------------------------------- HARRIS TRUST AND SAVINGS BANK By: /s/ Charles Howes ------------------------------------------- Title: Vice President ---------------------------------------- Van Kampen Prime Rate Income Trust Van Kampen Senior Floating Rate Fund August 24, 2001 Page 4 BNP PARIBAS By: /s/ Laurent Vanderzyppe ------------------------------------------- Title: Vice President ---------------------------------------- By: /s/ Marguerite L. Lebon ------------------------------------------- Title: Associate ---------------------------------------- DANSKE BANK A/S, CAYMAN ISLANDS BRANCH By: /s/ George Neofitidis ------------------------------------------- Title: Vice President ---------------------------------------- By: /s/ John A. O'Neill ------------------------------------------- Title: Assistant General Manager ---------------------------------------- Van Kampen Prime Rate Income Trust Van Kampen Senior Floating Rate Fund August 24, 2001 Page 5 Accepted and agreed to as of September 12, 2001 VAN KAMPEN PRIME RATE INCOME TRUST By: /s/ John Sullivan ------------------------------------------- Title: Treasurer ---------------------------------------- VAN KAMPEN SENIOR FLOATING RATE FUND By: /s/ John Sullivan ------------------------------------------- Title: Treasurer ----------------------------------------