Hypoxia/reoxygenation impairs endothelium-dependent relaxation in
isolated rat aorta.
Yokoyama, Shin, Ronald J. Korthuis, Joseph N. Benoit.
Department of Physiology and Biophysics, Louisiana State University
Medical Center, 1501 Kings Highway, Shreveport, Louisiana 71130
APStracts 2:0345R, 1995.
The effects of hypoxia followed by reoxygenation on endothelium
-dependent relaxation in isolated rat aorta were investigated.
Acetylcholine (ACh, 3 nM - 10 mM) and calcium ionophore A23187 (3 nM
- 300 nM)-induced endothelium dependent vasorelaxation of isolated
rat aortic vessel rings was impaired after 15 min of hypoxia followed
by 30 min of reoxygenation. Impairment of ACh-induced relaxation was
prevented by pretreatment with the combination of superoxide
dismutase (200 units/ml) and catalase (1000 units/ml).
Hypoxia/reoxygenation did not affect sodium nitroprusside (0.1 nM -
1mM)-induced endothelium independent relaxation nor the dissociation
constant of ACh to endothelial M3 muscarinic receptors. Propidium
iodide staining of the vascular endothelium revealed a significant
increase in the number of dead endothelial cells on the aortic vessel
rings following hypoxia/reoxygenation, but not on those pretreated
with superoxide dismutase and catalase. These results suggest that
hypoxia/reoxygenation impairs endothelium dependent relaxation of rat
aorta by a mechanism that involves oxidant-mediated endothelial cell
death.
Received 15 May 1995; accepted in final form 7 December 1995.
APS Manuscript Number R291-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 December 95