Secretin receptors in the rat kidney: adenylate cyclase activation and renal effects.

In previous studies it has been demonstrated that pharmacological administration of secretin can alter urine output. Whether the effect is due to a direct action on kidney was investigated by examining the effect of secretin on renal output, and determining whether there were secretin receptors and a secretin sensitive adenylate cyclase in the kidney. Secretin had an antidiuretic action on kidney when administered intravenously to anesthetized hydrated rats. In addition, binding sites for (125I)-secretin, and a secretin sensitive adenylate cyclase were identified in rat kidney. Binding was saturable and reversable and was half maximally inhibited by 1 X 10(-7) M synthetic porcine secretin. Autoradiographic studies revealed a high density of secretin binding sites in the outer medulla of the kidney, a region that is composed mainly of the thick ascending limb of the loop of Henle, and is also the major site of action for the antidiuretic hormone, vasopressin. The data indicate that a functional secretin receptor system exists in kidney which may have a physiological role in regulating urine output.