[Significance of atrial natriuretic peptide in heart failure: experimental findings]

We investigated the role of atrial natriuretic peptide (ANP) in a rat model of chronic heart failure (CHF) (coronary ligation) by four different studies: (1) stimulation of secretion of ANP by volume loading, (2) infusion of 1 micrograms/min of rat ANP (99-126), (3) correlations of pressure measurements of right atrium (RAP) and LVEDP versus plasma ANP levels and ANP mRNS versus infarct size, (4) blocking endogenous plasma levels of ANP with monoclonal ANP antibody. In severe CHF, volume loading did not exert a significant increase in plasma ANP, in contrast to moderate CHF or to normal animals. Infusion of ANP reduced RAP and LVEDP without significant increase in renal blood flow (radioactive microspheres) in rats with severe cardiac failure, in contrast to normal animals. A close relationship was found between LVEDP and atrial plasma levels. After injection of ANP antibody, filling pressures and systemic vascular resistance increased, indicating that removal of ANP may enhance arterial vasoconstriction or elevated endogenous ANP to exert a vasodilatory action in severe heart failure. Nevertheless, the cardiocirculatory effects, primarily on renal blood flow, appear to be limited.