EXCRETION OF ANTIDIURETIC ACTIVITY IN THE URINE OF CATS AND RATS AFTER ADMINISTRATION OF THE SYNTHETIC HORMONOGEN, Nα-GLYCYL-GLYCYL-GLYCYL-[8-LYSINE]-VASOPRESSIN (TRIGLYCYLVASOPRESSIN)

Abstract

SUMMARY The rate of excretion of antidiuretic activity in the urine of anaesthetized, water-loaded cats and of rats with familial diabetes insipidus after injection of single doses of lysine vasopressin (LVP) and of the long-acting analogue Nα-glycyl-glycyl-glycyl-[8-lysine]-vasopressin (triglycylvasopressin) has been studied by assays in water-loaded rats. The excreted antidiuretic material in all experiments resembled LVP and differed from triglycylvasopressin in the time course of the recorded response, the slope of the log dose—response relationship, and the index of persistence. The total antidiuretic activity excreted was a fraction of that of the injected LVP but equalled or exceeded the assayable activity of the dose of triglycylvasopressin injected. It is concluded that the excreted antidiuretic activity is due to LVP and that the excreted hormone originates from the triglycylvasopressin by enzymic activation in vivo.