Effect of papaverine on renin release in dogs in vivo and in vitro.

The effect of papaverine on renal function and renin release was investigated in dogs in vivo and in vitro. Intrarenal arterial infusion of 0.1 mg/kg/min of papaverine for 10 minutes caused a significant rise in renal blood flow, a significant decrease in renal vascular resistance, clearance and extraction ratio of creatinine and PAH and in the amount of filtered sodium, without altering arterial blood pressure. There was a significant increase in sodium excretion and in the excreted percentage of filtered sodium (TRFNa). Renin activity (PRA) of arterial blood and renal venous blood, veno-arterious PRA-difference and renin secretion increased significantly after papaverine infusion. In order to eliminate the effect of hemodynamic changes on renin secretion, the effect of papaverine (10(-5), 10(-4)M) was investigated in vitro in surviving canine kidney cortex slices. Papaverine caused a significant increase in renin release and in tissue cAMP concentration. This supports the assumption that the increase in renin secretion might be due to a direct effect on the juxtaglomerular apparatus, by blocking phosphodiesterase activity and by increasing the renal cAMP level.