Renal adenylate cyclase activation by amino acylated vasopressin and oxytocin

Two series of neurohypophysial peptide amino-acylated derivatives were tested for their ability to activate plasma membrane adenylate cyclase prepared from pig or rat kidney. They were firstly [8-lysine]-vasopressin-related derivatives (Na-[Glycyl-Cys]1-[8-Lysine]-vasopressin and Na-[Glycyl-Glycyl-Cys51-[8-Lysine]-vasopressin) and secondly oxytocin-related derivatives (Na-[Glycyl-Cys-a1)-oxytocin, Na-[Leucyl-Glycyl-Glycyl--Cys]-oxytocin, and Na-[Glycyl-Cys]-[2-0methyl tyrosine]-oxtocin). The maximal adenylate cyclase activation induced by these peptides was lower than that induced by their respective parent hormones. After incubation of these analogues with plasma membranes obtained from the renal medulla, no significant release of parent hormones occurred. Good qualitative correlations were observed between relative antidiuretic activities measured in vivo and relative potencies in activating adenylate cyclase. It was concluded that direct action of peptides tested on the kidney is at least partly responsible for their antidiuretic activity in vivo.