AJP - Endocrinology and Metabolism, Vol 255, Issue 6 E839-E842, Copyright © 1988 by American Physiological Society
Naloxone attenuates development of hypertension in two-kidney one-clip Goldblatt rats
M. Chen, J. G. Lee, R. L. Malvin and B. S. Huang
Department of Physiology, University of Michigan, Ann Arbor 48109.
The present experiments were designed to determine if an opiate antagonist
affects blood pressure in two-kidney one-clip Goldblatt rats. Male
Sprague-Dawley rats were divided into three groups. Group 1 received an
infusion of saline intraperitoneally via an osmotic pump and left renal
artery constriction (RAC). In group 2, rats were treated the same as group
1, except that they received an intraperitoneal infusion of naloxone (100
micrograms/h). Group 3 received the same infusion of naloxone without RAC.
Naloxone-infused Goldblatt rats showed a significantly lower systolic blood
pressure (SBP) than saline-infused Goldblatt rats (132 +/- 7 vs. 160 +/- 9
mmHg at day 14), but a higher SBP than control (132 +/- 7 vs. 106 +/- 1
mmHg). Infusion of naloxone did not significantly change SBP in
normotensive rats. Renal renin activity in the clipped kidney was higher
than in the nonclipped kidney in groups 1 and 2. Plasma renin activity
(PRA) in both groups of Goldblatt rats was higher than in group 3, but no
significant difference was found between the two groups of Goldblatt rats
(groups 1 and 2). Naloxone (1.5 microM) did not affect the basal secretion
of renin by isolated cortical slices from untreated rats. The present data
demonstrate that naloxone significantly attenuates the development of
hypertension in two-kidney one-clip rats. The attenuation of blood pressure
was not associated with the changes in PRA, renal renin activity, or plasma
aldosterone concentrations. The data support the hypothesis that the
endogenous opioid system may be involved in the development of renovascular
hypertension.
