AIMTo study the effects of rhBNP on the cardiac hemodynamics and renal function in dogs with heart failure.

METHODSCongestive heart failure in dogs was induced by either rapid ventricular pacing (RVP), 250 beats.min-1 for 7-14 days or by thoracic inferior vena cava constriction (TIVCC) to 1/2 its original diameter. When remarkable hemodynamic changes appeared rhBNP was infused intravenously at the dosage of 10, 30 and 100 ng.kg-1.min-1, each dose lasting 30 min.

RESULTSIn dogs (n = 7) with RVP heart failure, intravenous infusion of rhBNP at 10-100 ng.kg-1.min-1, caused decreases in mean arterial pressure (MAP), left ventricular systolic pressure (LVSP), LVdP/dtmax, pulmonary arterial pressure (PAP), left ventricular end diastolic pressure (LVEDP), total peripheral vascular resistance (TPR) and renal vascular resistance (RVR) dose-dependently, without significant changes in cardiac output (CO), LVdp/dt/P, left ventricular work (LVW), renal blood flow (RBF) and heart rate (HR). This suggested that rhBNP reduced the pre-load and after-load of the dogs with congestive heart failure but showed no distinct effect on the contractility of the heart. In dogs (n = 7) with TIVCC heart failure, there were remarkable decreases in MAP and LVEDP following the rhBNP infusion, without further reduction of CO, but no marked change in HR, LVSP, LVdP/dtmax, RAP and TPR. In both animal models of heart failure, there were significant increases in urine volume and sodium excretion which were more significant in TIVCC dogs than in RVP dogs.

CONCLUSIONrhBNP reduced the pre-load and after-load in dogs with heart failure and showed remarkable diuretic effect, but did not affect the contractility of the heart.