DIETARY VITAMIN-E INCREASES THE RESISTANCE TO LIPOPROTEIN OXIDATION AND ATTENUATES ENDOTHELIAL DYSFUNCTION IN THE CHOLESTEROL-FED RABBIT

This study was conducted to determine if vitamin E could reverse or at tenuate endothelial dysfunction following an atherogenic diet. Rabbits were initially fed 1% cholesterol for 4 weeks to induce endothelial d ysfunction. During the next 4 weeks the rabbits were fed either 1% cho lesterol + 0.2% vitamin E or 1% cholesterol alone, and were then kille d. Endothelium-dependent responses to acetylcholine, calcium ionophore A23187 and sodium nitroprusside (SNP) were studied in the preconstric ted perfused rabbit ear. Dietary vitamin E partially reversed the impa ired endothelium-dependent responses to acetylcholine associated with cholesterol feeding. The maximum decrease in perfusion pressure in res ponse to acetylcholine was 77.8% +/- 3.6% in control animals, 35.3% +/ - 2.6% in cholesterol-fed animals, and 49.1% +/- 4.7% in cholesterol vitamin E treated animals. The response to A23187 or sodium nitroprus side did not differ between the groups. The susceptibility of rabbit b eta-VLDL to oxidation was markedly decreased in the vitamin E treated animals as assessed by the formation of conjugated dienes. The formati on of lipid peroxidation products were also significantly inhibited by vitamin E. These data suggest that dietary vitamin E is beneficial in reducing the oxidative injury that may lead to the impairment of nitr ic oxide (NO)-mediated responses in early hypercholesterolaemia.