Angiotensin
Angiotensin is a polypeptide in the blood that causes vasoconstriction, increased blood pressure, and aldosterone release from the adrenal cortex. It is derived from the precursor molecule angiotensinogen, a serum globulin produced in the liver. It plays an important role in the renin-angiotensin system.
Secretion and Production
Angiotensins II, III, and IV have many effects on the human body. In the cardiovascular system, it acts as a vasoconstrictor. In the brain, it increases thirst sensation through the subfornical organ of the brain, decreases the response of the baroreceptor reflex, and increases the desire for salt. It increases the secretion of arginine vasopressin in the posterior pituitary and adrenocorticotropic hormone in the anterior pituitary. It also enhances the release of norepinephrine by direct action on postganglionic sympathetic fibers.
In the adrenal cortex, angiotensins cause the secretion of aldosterone. In the kidneys, it has a direct effect on the proximal tubules to increase sodium reabsorption. Although it slightly inhibits glomerular filtration by both indirectly and directly stimulating mesangial cell constriction. Its overall effect is to increase the glomerular filtration rate by increasing the renal perfusion pressure via efferent renal constriction.
Researchers have developed a form of synthetic angiotensin, but its potential medical uses are still being determined.