Renal kinin antagonism does not impair pressure-induced natriuresis

We studied the contribution of the renal kallikrein-kinin system to short-term electrolyte and water balance during baseline and during acutely elevated renal perfusion pressure (RPP) in the anesthetized dog. Renal blood flow, glomerular filtration rate, urine flow rate, renin secretion rate, and urinary excretion of sodium, potassium, prostaglandin E2 (PGE2), and kinins were measured at baseline RPP during intrarenal infusion of 0.9% saline or the competitive bradykinin analogue [D-Arg0,Hyp3,Thi5,D-Phe7,Thi8]bradykinin (50 micrograms/min), which blocks vascular and interstitial kinin receptors. RPP was then raised above baseline (control group 25%; kinin analogue group 22%) by ligating the celiac artery, the superior mesenteric artery, and the aorta distal to the renal arteries. Renal parameters were again measured during infusion of saline or the kinin analogue. The analogue had no effect on renal hemodynamic or excretory parameters at baseline perfusion pressures. Increasing RPP significantly increased urine flow rates and urinary sodium excretion rates (control group, 43 mumol/min; kinin analogue group, 55 mumol/min) in both groups of animals. Increasing pressure also tended to decrease renin secretion rate in both groups of animals; however, neither increased pressure nor infusion of the analogue affected urinary excretion of PGE2 or kinins. The results suggest that intrarenal kinins are not powerful short-term regulators of electrolyte and water balance and that an intact kallikrein-kinin system is not necessary to induce pressure diuresis and natriuresis.