Effect of vasopressin on rat urinary prostaglandin excretion

We studied the influence of rat renal prostaglandin on the effect of vasopressin, in vivo. In water-loaded rats, vasopressin induced a dose-related increase in total urinary prostaglandin E and prostaglandin F excretion and a decrease in total urine output. Urine excretion, which peaked in water-loaded controls during the first 2 h after loading, was suppressed in vasopressin-treated rats, however, their urinary prostaglandin E excretion was markedly enhanced. This increase in urinary prostaglandin E was suppressed by the simultaneous administration of indomethacin, and the 3-6 h post-administration peak in urine output of vasopressin-treated rats was inhibited. In hypophysectomized rats, urine excretion increased gradually after surgery, however, urinary prostaglandin E excretion decreased. Based on our present findings, we suggest that prostaglandin E produced in the rat kidney modulate the renal response to vasopressin.