[Does atrial antipressor natriuretic peptide play a pathophysiological role?].

In man, atrial natriuretic peptide (ANP) is released in pulsatile fashion into the right as well as left atrium in relation to atrial pressure and volume, i.e. wall tension. These responses are documented by a new radioenzymatic assay to measure ANP in human plasma relative to hemodynamic measurements during diagnostic cardiac catheterization, atrial pressure changes during various types of pacemaker stimulation, and changes in cardiopulmonary volumes during head-out water immersion or upper leg cuff occlusion. During the infusion of synthetic 1-28 alpha-human-ANP and attendant high normal plasma ANP concentrations, natriuresis and peripheral vasodilatation (using venous occlusion plethysmography) can be shown. The antipressor action of ANP, especially against angiotensin II (but less against noradrenaline), together with the antirenin and anti-aldosterone effects, suggest that the ANP system acts as a functional counterpart to the renin-angiotensin-aldosterone system. Accordingly, plasma ANP is elevated whenever renin is low (e.g. low-renin essential hypertension) and/or cardiopulmonary volume is elevated (e.g. cardiac or renal failure). In man, ANP probably plays a (patho-) physiological role, though its antipressor and natriuretic effects do not appear to be very potent.