Abstract
Arginine-, lysine- and leucine-vasopressin, injected intravenously into hydrated rats or dogs, caused different patterns of response in that urine osmolality fell much more slowly after the maximum increase following arginine-vasopressin, than after the other 2 preparations. Using 3 different parameters for antidiuretic response, arginine-vasopressin was somewhat more potent than leucine-vasopressin in both rats and dogs, considerably more potent than lysine-vasopressin in rats, and much more so in dogs.