Human plasma vasopressin response to potent loop-diuretic drugs.

To investigate the effect of potent loop diuretic drugs on the factors that control water excretion, immunoreactive plasma arginine vasopressin was measured at regular intervals for 6 h after intravenous administration of frusemide (40 mg) and piretanide (12 mg) in healthy adults. Despite a large diuresis there was no significant rise in plasma vasopressin compared to controls. Diuretic drug treatment caused small increases in plasma osmolality comparable to the control group, but no change in mean arterial blood pressure. The fall in blood volume of 7% within 1 h of frusemide administration was insufficient to stimulate vasopressin secretion. We conclude that loop diuretic drugs in the dose given have little effect on plasma vasopressin and osmolality but cause a small fall in blood volume in healthy adults.