VITAMIN-E REVERSES CHOLESTEROL-INDUCED ENDOTHELIAL DYSFUNCTION IN THERABBIT CORONARY CIRCULATION

Hypercholesterolaemia and atherosclerosis are associated with impaired endothelium-dependent vasodilation. In this study we have examined th e effects of vitamin E on cholesterol-induced endothelial dysfunction in the rabbit coronary circulation. Rabbits were maintained for 4 or 8 weeks on one of three experimental diets: (a) control chow, (b) 1% ch olesterol or(c) 1% cholesterol for the first half of the treatment per iod followed by 1% cholesterol + 0.2% vitamin E during the last half o f the treatment. After sacrifice, vasodilator responses to acetylcholi ne and sodium nitroprusside in the isolated perfused heart were studie d. Responses to sodium nitroprusside were similar between the groups w hereas responses to acetylcholine were significantly impaired in chole sterol-fed rabbits after both 4 and 8 weeks when compared to controls. In the cholesterol + vitamin E group, responses to acetylcholine were similar to controls and significantly greater than in the group recei ving cholesterol alone. These results show that both 4 and 8 weeks of choresterol-feeding induces an endothelial dysfunction in the coronary circulation of the rabbit, and that vitamin E protects against this d ysfunction. By comparing responses to acetylcholine in the 4 week chol esterol group with the 8 week cholesterol + vitamin E group it was sho wn that vitamin E may not only prevent further deterioration of the en dothelial function in the rabbit heart, but may also reverse the adver se effects of hypercholesterolaemia.