Water deprivation upregulates angiotensin II receptors in rat anterior pituitary.

Angiotensin II (ANG II) receptors were quantitated in pituitary glands of individual male Long Evans rats by autoradiography after incubation of 8-microns thick pituitary sections with 125I-[Sar1]ANG II. Rat anterior pituitary had a single class of high-affinity saturable ANG II receptors with a Bmax of 1,360 +/- 109 fmol/mg protein and a Ka of 0.510 +/- 0.03 X 10(9) M-1. Five days of water deprivation produced a marked increase in the number of anterior pituitary ANG II receptors (Bmax: 2,428 +/- 233 fmol/mg protein, a 79% increase, P less than 0.001) and a decrease in affinity for the ligand (Ka: 0.337 +/- 0.01 10(9) M-1, a 34% decrease, P less than 0.05). Our results suggest a role for anterior pituitary ANG II receptors in the regulation of fluid and electrolyte metabolism in the rat.