Renal Effects of Intrarenal Norepinephrine in the Nonclipped Kidney of Two-kidney, One Clip Goldblatt Hypertensive Rabbits

Park, Jong Kwan; Kim, Suhn Hee; Cho, Kyung Woo

Abstract

Roles of the nonclipped kidney in the development and maintenance of the high blood pressure in two- kidney, one clip hypertension remain to be defined. It has been known that the pathophysiology of hypertension is different by the presence or absence of the contralateral kidney in renal hypertension. The present study was undertaken to evaluate the effects of intrarenal norepinephrine in the nonclipped kidney exposed to the high blood pressure. Experiments were performed in 7-day two-kidney, one clip Goldblatt hypertensive and sham-operated normotensive rabbits. The basal levels of renal plasma flow and urine flow, and urinary excretion of electrolytes were higher in the nonclipped kidney of two-kidney, one clip Goldblatt hypertensive than in the corresponding kidney of sham-operated normotensive rabbits. Intrarenal infusion of norepinephrine increased renal perfusion resistance, and decreased renal hemodynamics and renal excretory function in a dose-dependent manner in both hypertensive and normotensive rabbits. The renal hemodynamics and excretory responses to intrarenal norepinephrine infusion were attenuated in two-kidney, one clip Goldblatt hypertensive rabbits. The changes by norepinephrine infusion of the renal excretory function were closely correlated with those in glomerular filtration rate or renal plasma flow. These results suggest that the impaired vascular reactivity in the nonclipped kidney is one of the early changes appeared in the course of multifactorial derangements in renal hypertension and that the impairment may be an adaptive response of the kidney to high blood pressure.