Vascular reactivity of isolated perfused kidneys from normotensive, renal hypertensive and spontaneously hypertensive rats.

By means of an isolated kidney perfusion technique, reactivities of renal body vessels to electrical stimulation of renal plexus and intravascular administrations of low dosed norepinephrine and epinephrine were determined in the spontaneously hypertensive rats of Wistar strain, normotensive Sprague-Dawley rats and Sprague-dawley rats with renal hypertension of the same sex and as equal as possible with respect to age and body weight. The basal vascular resistance as indicated by the perfusion pressure caused by the same rat of perfusion was significantly higher in the renal hypertensive group. Both electrical stimulation of the renal plexus and intravascular administrations of catecholamines caused a rise of perfusion pressure. Analysis of the dose-response relationship reveals that in the dose range used, the sensitivities to electrical stimulation and to norepinephrine are significantly higher in the normotensive than the hypertensive groups. The results indicate that structural change in the blood vessels is more important than the adrenergic actions of low intensity in the cause of high resistance of blood flow in hypertensive subjects at least in the kidney.