This study aimed to examine whether α-human atrial natriuretic peptide (α-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 α-hANP at a dose of 0.03-0.04 μg/kg per minute (n=8). Studies were also done during IV infusion of saline or nitroglycerin (NG) at a dose of 10-15 μg/kg per minute in another group of subjects (n=6). LBNP decreased central venous pressure (CVP) and the LA and LV diameter. α-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 α-hANP did not alter the LA and LV diameter at rest or with LBNP. In another group of subjects (n=4), we observed that α-hANP caused comparable decreases in CVP and pulmonary capillary wedge pressure. These data suggest that ANP may dilate the cardiac chambers in humans.
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