Mechanisms Controlling Release of Atrial Natriuretic Peptide

the myoendocrine cells in the atria of the mammalian heart synthesize and secrete a hormone called atrial natriuretic peptide (ANP), which causes natriuresis and diuresis. Pharmacological studies in the isolated heart suggest that cytosolic calcium may regulate the release of ANP. The concentration of calcium in heart muscle cells depends on many factors, such as the action of humoral substances, cardiac nerve activity, heart rate, and resting length of the myocardial fibers. These factors may also contribute to the regulation of ANP secretion. The most important factor in the control of ANP release appears to be fiber length. Experimental and clinical observations indicate a direct correlation between secretion rate and atrial filling pressure. Little is known about the role of heart rate, autonomic nerve activity, and humoral factors in ANP regulation; further investigation is required.