Different effects of alpha-human atrial natriuretic peptide and nitroglycerin on cardiac dimensions in humans.

This study aimed to examine whether alpha-human atrial natriuretic peptide (alpha-hANP) alters cardiac dimensions in humans. Left atrial (LA) and left ventricular diastolic (LV) diameters were measured by echocardiography at control and with lower body negative pressure (LBNP) at -10 and -20 mmHg during intravenous (IV) infusion of saline or alpha-hANP at a dose of 0.03-0.04 microgram/kg per minute (n = 8). Studies were also done during IV infusion of saline or nitroglycerin (NG) at a dose of 10-15 micrograms/kg per minute in another group of subjects (n = 6). LBNP decreased central venous pressure (CVP) and the LA and LV diameter. alpha-hANP lowered CVP at rest and with LBNP at -10 and -20 mmHg compared with corresponding values during saline infusion; NG produced comparable decreases in CVP, which suggests that decreases in venous return caused by the two drugs were similar. However, NG decreased, but alpha-hANP did not alter the LA and LV diameter at rest or with LBNP. In another group of subjects (n = 4), we observed that alpha-hANP caused comparable decreases in CVP and pulmonary capillary wedge pressure. These data suggest that ANP may dilate the cardiac chambers in humans.