Haemodynamic effects of atrial natriuretic peptide in rats with heart failure.

Plasma atrial natriuretic peptide (ANP), a hormone secreted by the heart, is elevated in cardiac failure. In the aim to study the role of ANP in cardiac failure, the haemodynamic response to ANP was examined in rats with chronic heart failure produced by coronary artery ligation. Plasma ANP was clearly elevated in all infarcted rats before ANP injection as compared with controls. ANP lowered the blood pressure and impaired cardiac contractility, as measured by the maximal positive value of the first derivative of the pressure signal, in a dose-dependent manner. The blood pressure lowering effects of ANP were attenuated in rats with cardiac failure. We conclude that rats with experimentally induced heart infarct are partially resistant to the haemodynamic effects of ANP.