Diuretic effect induced by intrarenal infusion of pinacidil in anesthetized dogs.
The diuretic action of pinacidil, a new vasodilating antihypertensive agent, was studied using anesthetized dogs. Intrarenally administered pinacidil (0.4, 2.0 and 10 micrograms/kg/min) produced a dose-related increase of renal blood flow, without altering mean arterial pressure. The glomerular filtration rate significantly increased only with the highest dosage. Pinacidil caused a dose-related augmentation of urine formation and, when given at 10 micrograms/kg/min, increased urine flow and urinary excretion of electrolytes to about 10 times and 3 to 9 times over the respective control value. In comparison, hydralazine (4.0 and 20 micrograms/kg/min) produced no significant diuretic action and bradykinin, given at a dose (0.02 micrograms/kg/min) equipotent to pinacidil (10 micrograms/kg/min) with respect to increasing renal blood flow, was less effective. Pinacidil administration significantly increased the fractional excretion of phosphate. Thus, pinacidil-induced diuresis seems to be due mainly to the vasodilating effect on renal vessels, with some contribution from an inhibitory effect on sodium reabsorption in the proximal tubules.
PubMed Abstracts
PubMed Abstracts