Binding and activation properties of angiotensin II in dispersed rat anterior pituitary cells

The properties of angiotensin II receptors were studied in isolated rat anterior pituitary cells prepared by trypsin digestion. Angiotensin II bound in a time- and temperature-dependent manner to pituitary cells, with Kd of 4.1 x 10(-9) M. The heptapeptide, des-Asp1-angiotensin II, had only one-tenth of the affinity of the octapeptide (Ki = 5.5 x 10(-8) M). These two peptides displayed a similar potency ratio in their ability to stimulate ACTH release from pituitary cells. These results indicate that angiotensin II may play a regulatory role in controlling ACTH secretion from the pituitary gland.