Effects of Angiotensin II and Noradrenaline on Intrarenal Haemodynamies in the Rat*

Abstract

The haemodynamic effects of angiotensin II and noradrenaline were studied in the rat kidney. These pressors were given by intravenous infusion in stepwise increasing doses. Intrarenal haemodynamics were analyzed by the 133xenon washout technique, 85krypton autoradiography and silastic casting of the renal vascular tree. Angiotensin II induced significant changes in intrarenal haemodynamics before any changes in systemic blood pressure were detected. The decrease in mean renal blood flow (2.91 ml.min-1.g-1 in controls, 1.76 ml.min-1.g-1 in rats given 50 mug of angiotensin II.kg-1.h-1) reflects a reduction in component I blood flow rate (from 3.9 to 2.9 ml.min-1.g-1) as well as a decrease in the fraction of total renal blood flow supplied to component I of the washout curve (from 84% to 62%). With noradrenaline an increase in total renal resistance occurred simultaneously with the elevation of mean arterial blood pressure. The resulting reduction in mean renal blood flow (from 2.76 ml.min-1.g-1 in controls to 1.55 ml.min-1.g-1 in rats given 1000 mug of noradrenaline kg-1.h-1) reflects a decrease in component I blood flow rate with lower infusion rates and a drop in component I flow fraction (from 82% to 52%) whith higher doses. In contrast to canine kidneys, no evidence for a patchy cortical vasoconstriction was found in the rat. Using autoradiography it was possible to attribute component I to the renal cortex and subcortical area of the kidney.

Intrarenal Blood Flow Distribution in the Genetically Hypertensive Rat

“…distribution similar to that found by others [4,13] using 133Xe in rats though our flow rates to compartments I and 11 are slightly lower. Our mean flow index for N rats is within the range found by others using l33Xe in rats [4.13.14] but is slightly lower than that obtained by 8(iRb methods [6,15] and microspheres [16,17], The problems and limitations in interpretation of inert gas washout data have been discussed by other workers [5.6,8], We have limited our study to a comparison be tween two groups of animals under similar conditions and have shown that there is a difference in renal haemody namics between GH and N rats under the conditions of our study.…”

Efficacy of two‐route chemotherapy using cis‐diamminedichloroplatinum(II) and its antidote, sodium thiosulfate, in combination with angiotensin II for rat liver tumor

“…(1) AT-I1 selectively increased tumor blood flow (Suzuki et al, 1981) and consequently delivery of CDDP to the tumor; and (2) transient inhibition of CDDP delivery to the kidney occurred during AT-11-induced hypertension, as AT-I1 decreases renal blood flow (Rentsch et al, 1976;Tvete et al, 1981), so that post-administration of STS to CDDP became feasible.…”

Redistribution of Intrarenal Blood Flow After Carotid Artery Occlusion in the Rat

“…In many instances it has been difficult to attribute the observed changes directly to the experimental conditions and to separate them from effects mediated by variations in per fusion pressure [21,22].…”