ATRIAL NATRIURETIC PEPTIDE (ANP)
A hormone produced by the heart, atrial natriuretic peptide (ANP), increases sodium excretion and decreases blood pressure and blood volume.

ANP is released into the bloodstream in response to stretching of the atrial muscle cells by increased blood volume.

ANP has the following physiological effects:

• Increases glomerular filtration rate by dilating afferent arterioles
• Inhibits the collecting ducts from reabsorbing sodium, both directly and indirectly (by inhibiting aldosterone secretion)
• Inhibits release of renin

The renin-angiotensin system and ANP function antagonistically in the maintenance of fluid/electrolyte balance and blood pressure.