Attenuation of clonidine-induced vascular alpha 1-antagonistic action in hypercholesterolemic rabbit common carotid arteries

We examined the effect of hypercholesterolemia on vasodilatory responses to clonidine in isolated and perfused rabbit common carotid arteries that had been preconstricted by phenylephrine. The responses decreased in rabbits fed an atherogenic diet for 4 or 8 weeks, whereas the responses to acetylcholine, nitroglycerin and substance P were not changed after the cholesterol feeding. Attenuated responses to clonidine were maintained for 24 weeks after cessation of the atherogenic diet, suggesting that this response might be an early marker of atherosclerosis.