Long-term effects of B-type natriuretic peptide infusion after acute myocardial infarction in a rat model.

Introduction: The effects of exogenous B-type natriuretic peptide (BNP) on postmyocardial infarction (MI) are not known. We tested the hypothesis that in vivo infusion of BNP Would improve cardiac function and affect left ventricular (LV) remodeling in an experimental model of MI. Methods: MI was induced by coronary ligation in rats and confirmed by echocardiography. 19 rats were randomized to I of 3 groups: sham (n = 7), MI + saline (n = 5), MI + BNP (400 ng.kg(-1).minute(-1)) (n = 7). Infusions were delivered for 7 days via venous catheters tunneled to an infusion pump. Rats were followed for 8 weeks. Echocardiography, hemodynamics, histology, and in vivo and ex vivo pressure-volume relationships were examined. Results: LV systolic pressure, LV dP/dt(max), and infarct size improved with BNP treatment versus control MI group (132 +/- 4 vs. 110 +/- 2 tran Hg, 8097 +/- 317 vs. 5816 +/- 378 mm Hg/s, 19.3% +/- 1.6% vs. 23.3% +/- 1.9%, respectively; all P < 0.05). Ex vivo end-diastolic pressure-volume relationship demonstrated reduced diastolic dysfunction after BNP therapy (P < 0.05 vs. control MI). Serum BNP levels confirmed delivery of BNP. Conclusions: We demonstrate beneficial effects on LV function and decreased LV remodeling with BNP infusion in an experimental model of acute MI.