Systemic vasoconstriction induced by inhibition of nitric oxide synthesis is attenuated in conscious dogs with heart failure

Abstract

Study objective – The aim was to test the hypothesis that endothelium dependent vasomotor control is impaired in heart failure. Design and subjects – The haemodynamic effects of N^G-nitro-L-arginine (NNA), an inhibitor of nitric oxide synthesis, were studied in five dogs with and without pacing induced heart failure. Main results – In healthy dogs, NNA increased total peripheral resistance and arterial pressure, decreasing cardiac output and heart rate. These effects were partially reversed by L-arginine. In dogs with heart failure, NNA did not change any haemodynamic variable. However, L-arginine decreased total peripheral resistance. Conclusions – These findings support a physiological role for endothelium derived nitric oxide in control of vascular resistance and are in agreement with the hypothesis that endothelium dependent vasomotion may be impaired in heart failure.