All of the following statements concerning ANP are true Except
ANP is a polypeptide composed of 28 amino acids that is secreted by endocrine cells in the atria. ANP acts at the kidney to increase sodium excretion, and is secreted in response to blood volume expansion or increased sodium chloride intake. Circulating levels of ANP are increased in congestive hea failure, a condition in which atrial pressure is chronically elevated. The exact mechanisms for the natriuretic effect are not completely known. ANP increases glomerular filtration rate without a sustained increase in renal blood flow, which suggests that the peptide may constrict efferent aerioles. Fuhermore, ANP relaxes mesangial cells in the glomeruli, thereby increasing surface area available for filtration. Finally, ANP may directly inhibit sodium reabsorption by renal tubules. The actions of ANP are generally opposite to those of the renin-angiotensin-aldosterone system. ANP inhibits the secretion of renin and aldo sterone.ANP produces its effects by increasing intracellular formation of cGMP. The ANP receptor has a cytoplasmic domain with guanylyl cyclase activity, which is increased by hormone-receptor binding.
Its secretion is increased by an increase in blood volume
It increases glomerular filtration rate
It inhibits rennin secretion
Its effects are mediated by increased cyclic AMP
Renal physiology