Water deprivation upregulates angiotensin II receptors in rat anterior pituitary

Abstract

Angiotensin II (ANG II) receptors were quantitated in pituitary glands of individual male Long Evans rats by autoradiography after incubation of8-pm thick pituitary sections with r'z5I-[Sarr]ANG II. Rat anterior pituitary had a single class of high-affinity saturable ANG II receptors with a -B.". of 1,360 i 109 fmol/mg protein and a K, of 0.510 t 0.03 x 10'g M-r. Five days of water deprivation produced a marked increase in the number of anterior pituitary ANG II receptors (B-""12,428 i 233 fmol/mg protein, a 79% increase, P < 0.001) and a decrease in affinity for the ligand (K,:0.337 a 0.01 10'g M 1, a 34% decrease, P < 0.05). Ou¡ results suggest a role fbr anterior pituitary ANG II receptors in the regulation of fluid and elect¡ol,te metabolism in the rat.