AMENDMENT NO. 1 AND AGREEMENT TO REVOLVING CREDIT AND TERM LOAN AGREEMENT

Exhibit 10.12(b)

AMENDMENT NO. 1 AND AGREEMENT TO

REVOLVING CREDIT AND TERM LOAN AGREEMENT

This Amendment No. 1 and Agreement dated as of June 12, 2008 to the Revolving Credit and Term Loan Agreement (this “ Amendment No. 1 and Agreement ”), is entered into among Atlas Pipeline Partners, L.P., a Delaware limited partnership (“ Borrower ”), the Subsidiaries of the Borrower identified as “Guarantors” on the signature pages hereto (the “ Guarantors ”), the Lenders signatory hereto and Wachovia Bank, National Association, in its capacity as administrative agent for the Lenders (in such capacity, the “ Administrative Agent ”) and amends the Revolving Credit and Term Loan Agreement dated as of July 27, 2007 (as amended, supplemented or otherwise modified from time to time, the “ Credit Agreement ”) entered into among the Borrower, the Guarantors named therein (collectively, the “ Guarantors ”), the institutions from time to time party thereto as Lenders (the “ Lenders ”), the Administrative Agent and the other agents and arrangers named therein. Capitalized terms used herein and not otherwise defined herein shall have the meanings ascribed to them in the Credit Agreement.

W I T N E S S E T H:

WHEREAS, Section 12.04 of the Credit Agreement provides that the Credit Agreement may be amended, modified and waived from time to time;

WHEREAS, the Borrower has requested that the Administrative Agent and the Lenders agree to amend the Credit Agreement in certain respects as set forth herein and the Lenders and the Administrative Agent are agreeable to the same, subject to the terms and conditions set forth herein;

NOW, THEREFORE, in consideration of the premises and for other good and valuable consideration (the receipt and sufficiency of which are hereby acknowledged), the parties hereto hereby agree as follows:

Section 1. Amendment to Credit Agreement

(a) Amendments to Section 1.02 of the Credit Agreement . Section 1.02 of the Credit Agreement is hereby amended as follows:

(i) The definition of “ Consolidated EBITDA ” is hereby amended and restated as follows:

“ Consolidated EBITDA means, for any trailing twelve-month period, the sum of (i) Consolidated Net Income for such period, plus without duplication (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, extraordinary, unusual or non-recurring charges relating to premiums or penalties paid to counterparties, in connection with the breakage, termination or unwinding of Hedging Agreements to the extent such charges are financed with or paid for out of proceeds of an Equity Offering by the Borrower and other non-cash charges (other than a non-cash charge resulting from an accrual of a reserve for any cash charge in any future period) to Consolidated Net Income including non-cash losses resulting from mark to market accounting of Hedging Agreements, minus without duplication (iii) non-cash credits to Consolidated Net Income including non cash gains resulting from mark to market accounting of hedging agreements; provided that with respect to that portion of the Borrower’s Consolidated EBITDA attributable to the Acquired Business, (a) such portion of Consolidated EBITDA for the fiscal quarter ending December 31, 2007 shall be calculated by

annualizing the Consolidated EBITDA of the Acquired Business for such fiscal quarter and the previous fiscal quarter and (b) such portion of Consolidated EBITDA for the fiscal quarter ending March 31, 2008 shall be calculated by annualizing the Consolidated EBITDA of the Acquired Business for such fiscal quarter and the two previous fiscal quarters. For purposes of this Agreement, Consolidated EBITDA shall be adjusted on a pro forma basis, in a manner reasonably acceptable to the Administrative Agent, to include, as of the first day of any applicable period, without duplication, (x) the Anadarko Formation or any acquisition permitted pursuant to Section 9.03(i) closed during such period, including, without limitation, adjustments reflecting any non-recurring costs and any extraordinary expenses of the Anadarko Formation or any acquisition permitted pursuant to Section 9.03(i) closed during such period calculated on a basis consistent with GAAP and Regulation S-X of the Securities Exchange Act of 1934, as amended, or as approved by the Administrative Agent and (y) any Pro Forma Cost Savings.

(ii) The definition of “ Loan Documents ” is hereby amended and restated as follows:

“ Loan Documents means this Agreement, the Notes, the Guaranty Agreements, all Letters of Credit, all Letter of Credit Agreements, the Fee Letter, the Security Instruments, the Increase Joinder, if any, and each other document, instrument, certificate and agreement executed and delivered by the Borrower or any Subsidiary thereof in connection with this Agreement or otherwise referred to herein or contemplated hereby (excluding any Hedging Agreement and Cash Management Agreements), all as may be amended, restated, supplemented or otherwise modified from time to time.”

The definition of “ Revolver Facility ” is hereby amended and restated as follows:

“ Revolver Facility means the credit facility as described in and subject to the limitations set forth in Section 2.01(a)(i) hereof (as the same may be decreased pursuant to Section 2.03(a) or increased pursuant to Section 2.12(a) ).”

(iii) The following definitions shall be added in alphabetical order to read as follows:

“ Decline Commitment ” means the agreement of each Term Lender who has executed clause (2)(A) of the signature page to the Amendment No. 1 and Agreement dated as of June 10, 2008 to the Credit Agreement to decline the entire portion of the prepayment of its Term Loans pursuant to Section 3.01(b)(vii) of this Agreement.

“ Increase Effective Date has the meaning assigned to such term in Section 2.12(a) .

“ Incremental Loan ” has the meaning assigned to such term in Section 2.12(c) .

“ Incremental Loan Commitment ” has the meaning assigned to such term in Section 2.12(a) .

“ Incremental Loan Maturity Date ” has the meaning assigned to such term in Section 2.12(c) .

“ Increase Joinder ” has the meaning assigned to such term in Section 2.12(c) .”

“ OID ” has the meaning assigned to such term in Section 2.12(c) .

-2-

(b) Amendments to Section 3.01(b) of the Credit Agreement . Section 3.01(b) of the Credit Agreement is hereby amended as follows:

(i) Clause (vii) is amended and restated as follows:

“(vii) So long as any Term Loans remain outstanding, any Term Loan Lender may elect to decline the entire portion of the prepayment of its Term Loans pursuant to Section 3.01(b) by delivery of a completed Notice of Election to the Administrative Agent by telecopy at least one Business Day prior to the applicable prepayment date, in which case the aggregate amount of the prepayment that would have been applied to prepay Term Loans but was so declined shall be re-offered to those Term Loan Lenders under this Agreement who have initially accepted such prepayment (such re-offer to be made to each such Term Loan Lender based on the percentage which such Term Loan Lender’s Term Loans represents of the aggregate Term Loans of all such Term Loan Lenders who have initially accepted such prepayment). In the event of such a re-offer, the relevant Lenders may elect to decline in such Notice of Election all of the amount of such prepayment that is re-offered to them, in which case the aggregate amount of the prepayment that would have been applied to prepay such Term Loans pursuant to such re-offer but was so declined shall be applied to repay Revolver Loans; provided that no reduction of the Revolver Commitments shall be required in connection with such prepayment. Any amounts remaining following repayment of the Revolver Loans shall be returned to the Borrower. In the absence of delivery of a completed Notice of Election with respect to any prepayment at least one Business Day prior to the applicable prepayment date, such Lender shall automatically be deemed to have accepted such prepayment and any re-offer in respect thereof.”

(c) Amendments to Article II of the Credit Agreement . Article II of the Credit Agreement is hereby amended by adding Section 2.12 as follows:

“ Section 2.12 Increase in Commitments .

-3-