AJP - Regulatory, Integrative and Comparative Physiology, Vol 261, Issue 4 934-R938, Copyright © 1991 by American Physiological Society
Peripheral vascular resistance and regional blood flows in hypertensive Dahl rats
M. A. Boegehold, L. J. Huffman and G. A. Hedge
Department of Medicine, West Virginia University School of Medicine, Morgantown 26506.
The aim of this study was to determine whether different organs undergo
similar increases in vascular resistance with hypertension in the Dahl
salt-sensitive rat. Cardiac output and organ blood flows were measured with
microspheres in anesthetized salt-sensitive and salt-resistant rats fed a
high- (7%) or normal- (0.45%) salt diet for 4 wk. High salt intake produced
hypertension only in salt-sensitive rats. Cardiac index for the
hypertensive group was not different from that for any other group, whereas
peripheral resistance index was elevated in proportion to arterial
pressure. There were no differences among groups in the fraction of cardiac
output supplying the myocardium, intestine, diaphragm, spinotrapezius
muscle, or gracilis muscle. The fraction of cardiac output supplying the
kidneys was lower in salt-sensitive rats (13%) than in salt-resistant rats
(17%) and, among salt-sensitive rats, lowest in the high-salt group.
Therefore all the organs studied contribute to increased total peripheral
resistance in the hypertensive Dahl rat, with the renal vasculature
undergoing the largest resistance increase. Different muscles undergo
similar increases in vascular resistance, despite differences in the
microvascular abnormalities accompanying salt-induced hypertension.
