EFFECTS OF DIETARY FATS, ALPHA-TOCOPHEROL AND BETA-CAROTENE SUPPLEMENTATION ON AORTIC RING SEGMENT RESPONSES IN THE RAT

We examined the effects of vitamin supplement on the vascular smooth m uscle response of rats fed four different oil diets, after a 20-day fe eding period Male Sprague Dawley rats were fed diets containing 15% of each hazelnut, corn, olive or fish oils, with/without 30 mg/kg beta-c arotene and 500 mg/kg dl-alpha-toco-pherylacetate. After the feeding p eriod, plasma retinol, alpha-tocopherol, cholesterol, HDL and tri-acyl glyceride concentrations and aortic ring segment responses to KCl (70 mM), phenylephrine and acetylcholine (maximal tension, maximal relaxat ion and pD(2) or -log ED(50)) were measured. The intake of vitamin-sup plemented diets increased plasma alpha-tocopherol levels in rats fed h azelnut or fish oil, while retinol concentration was unaffected Also, the vitamin supplement counteracted the specific hypercholesterolemic effect of hazelnut oil intake. The addition of a vitamin supplement au gmented acetylcholine pD(2) values in aortic ring segments of rats fed corn oil (p < 0.001), revealing that arteries were more prone to indu ced relaxation under this dietary condition. It also lowered the maxim al ring tension in response to phenylephrine in rats fed hazelnut or o live oil. These results indicate that the intake of alpha-tocopherol a nd beta-carotene supplement can modulate the effect of dietary fat typ e on aortic ring segment responses to pharmacological agents in the ra t.