ANP (atrial natriuretic peptide) is released by the cells of the atria of the heart in response to changes in blood volume and pressure. Specifically, ANP is secreted by the atrial myocytes, which are specialized cells located in the walls of the atria.
When the atrial myocytes are stretched, such as during an increase in blood volume or pressure, ANP is released into the bloodstream. ANP acts to reduce blood volume and pressure by increasing the excretion of sodium and water by the kidneys, which in turn reduces the amount of fluid in the body.
ANP can also be released by the heart in response to other stimuli, such as stress and exercise. In addition to its effects on fluid and electrolyte balance, ANP has other effects on the cardiovascular system, including the relaxation of blood vessels and the inhibition of the production of other hormones, such as renin and aldosterone, that can raise blood pressure.
