Ethacrynic acid, a potent inhibitor of sodium reabsorption in the ascending limb of Henle's loop, produces a sharp rise in renal venous renin activity within 5 min after intravenous administration in anesthetized dogs. This response persists when volume depletion is prevented by returning urinary outflow to the femoral vein. Comparable studies with chlorothiazide, a diuretic with little or no effect on the medullary portion of the ascending limb of the loop of Henle, failed to produce a significant increase in renal venous renin activity.
C. Robert Cooke, Torrey C. Brown, Barry J. Zacherle, W. Gordon Walker