Al. Stewartlee et al., DIFFERENCES IN ONSET OF IMPAIRED ENDOTHELIAL RESPONSES AND IN EFFECTSOF VITAMIN-E IN THE HYPERCHOLESTEROLEMIC RABBIT CAROTID AND RENAL-ARTERIES, Journal of cardiovascular pharmacology, 25(6), 1995, pp. 906-913
Hypercholesterolemia (HC) is known to be associated with impaired endo
thelium-mediated responses in the vasculature. Evidence suggests that
increased levels of reactive oxygen species (ROS) in the vessel wall m
ay contribute to the impairment by decreasing the biological activity
of endothelium-derived relaxing factor (EDRF). We compared the relativ
e onset of HC-induced impairment of endothelial responses in the carot
id and renal arteries and investigated the potentially beneficial effe
ct of the antioxidant vitamin E. Rabbits were fed a 1% cholesterol-enr
iched diet for 4 and 8 weeks, and vascular responses were compared usi
ng isolated ring segments of the carotid and renal arteries. In the ca
rotid artery, relaxant responses to acetylcholine (ACh) were significa
ntly and progressively impaired after 4 and 8 weeks; in the renal arte
ry, however, responses were only slightly impaired after 8 weeks. Ther
e were no changes in responsiveness to A23187 or sodium nitroprusside
(SNP) in either artery, We tested the effect of 0.2% vitamin E by addi
ng it to the diet for 4 weeks, after an initial 4-week of feeding of 1
% cholesterol alone. Vitamin E reversed impaired responses to ACh in t
he carotid but not the renal artery and also enhanced relaxant respons
es to A23187. We conclude that the carotid artery is more susceptible
than the renal artery to HC-induced endothelial impairment and that RO
S may play a role in this impairment in the carotid artery but not in
the renal artery.