Effects of Atrial Natriuretic Peptide on Left Ventricular Performance in Conscious Dogs Before and After

Atrial natriuretic peptide (ANP) has potent vasodilatory and natriuretic actions and may have therapeutic benefit in conges-tive heart failure (CHF). These benefits may be offset by a negative inotropic effect of ANP seen in isolated preparations. However, ANP’s integrated effect on left ventricular (LV) con-traction and relaxation, independent of loading conditions, both under normal conditions and after CHF, is not known. We studied six conscious dogs, instrumented to measure LV and left atrial pressures and to determine LV volume from three dimensions. ANP produced significant (P,.05) decreases in LV end-systolic pressure (101.2 6 11.8 versus 91.7 6 11.2 mm Hg, P,.05) in normal dogs and in dogs with CHF (93.1 6 6.4 versus 87.1 6 4.4 mm Hg, P,.05). ANP also caused signifi-cant reductions of the slope of end-systolic pressure-end-sys