Regional vascular capacitance in rabbit one-kidney, one clip hypertension.

Abstract

SUMMARY One-kidney Goldblatt hypertensive rabbits (New Zealand White) were studied after durations of renal artery clipping that varied from 6 to 17 days. Measurements included arterial pressure (ABP), iliac venous pressure (IVP), left atrial pressure (LAP), cardiac output (CO) (by thermodilution), blood volume (BV), cardiopulmonary volume (CPV), and hind leg thermodilution volume (HLV). These were determined at steady-state as well as during acute blood volume expansion. In sham-clipped animals, ABP was 74 ± 1 mm Hg. This increased to 92 ± 3 mm Hg by 6 to 9 days post-clipping, to 96 ± 3 mm Hg by 10 to 13 days, to 89 ± 4 mm Hg by 14 to 17 days. CO remained near 150 ml/min kg until Day 13 and fell to 127 ± 8 ml/min kg at 14 to 17 days because of a fall in heart rate. Blood volume and stroke volume did not change significantly from 62 ± 1 ml/kg and 0.60 ± 0.04 ml/kg, respectively. The development of hypertension was due entirely to changes in peripheral resistance. CPV was 8. Even a small shift of volume from the venous to the arterial circulation would raise arterial blood pressure greatly," and it has been proposed that established hypertension is in part maintained by an imbalance between a normal circulating blood volume and a decreased volume capacitance of the vasculature. 12 -l3 From the Department of Physiology, University of Toronto, Toronto, Ontario.Supported by Ontario Heart Foundation Grant 1-31. Address for reprints: U. Ackermann, Ph.D., Department of Physiology, Medical Science Building, University of Toronto, Toronto, Ontario, Canada M5S 1A8.Received March 12, 1982; revision accepted February 25, 1983. Although it has been argued that reduced venous distensibility in hypertension is less likely to be an effect of the raised arterial pressure and more likely to be one of its contributing causes, 5 it is not known whether changes in distensibility are progressive; it is not known whether there are differences among tissues with respect to such changes nor what effect these changes have on regional vascular volumes either at steady state or during an acute volume stress.The purpose of these experiments was to measure, at steady-state and during acute blood volume expansion, the volume in the cardiopulmonary region and in the hindleg region of rabbits with one-kidney Goldblatt hypertension of increasing duration. MethodsExperiments were performed on 36 male New Zealand White rabbits, anesthetized with sodium pentobarbital (25 mg/kg) injected into a marginal ear vein.

Sympathetic Activity, Vascular Capacitance, and Long-Term Regulation of Arterial Pressure

“…Very similar results (i.e. increased central but not total blood volumes) have been reported in experimental hypertension in animals44, 45. Thus, redistribution of circulating blood without a change in its total volume could be an important aspect of the hemodynamics of hypertension.…”

Venodilating Action of Nipradilol (K-351) in the Pithed Rat Pretreated with Dihydroergotamine

“…It has been reported that venous compliance is decreased and venous contractility is enhanced in human essential hypertension (10)(11)(12) and also in experimental hypertensive animals (13)(14)(15)(16).…”