The endothelium-dependent relaxation of rabbit aorta: effects of antioxidants and hydroxylated eicosatetraenoic acids.
Acetylcholine (ACh) induced concentration-dependent relaxations of rabbit aortic strips precontracted with noradrenaline. The relaxations were abolished if the endothelium of the strips was disrupted. Three different antioxidants (butylated hydroxytoluene, dithiothreitol and alpha-tocopherol) reversed the endothelium-dependent vasodilation in a concentration-dependent manner. However, the antioxidant ascorbic acid did not alter the vasodilatation. The hydroxylated eicosatetraenoic acids 5-HETE, 12-HETE, 15-HETE and 5,12-diHETE had no effect on aortic strips under basal or induced tension. These results suggest, that (non-cyclo-oxygenase) oxidation processes, insensitive to the action of ascorbic acid, represent a crucial step in the endothelium-dependent dilatation of rabbit aorta by ACh. The hydroxylated fatty acids tested are unlikely to mediate this relaxation.
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001011:Aorta / Q000187:drug effects; D001205:Ascorbic Acid / Q000494:pharmacology; D004727:Endothelium / Q000187:drug effects / Q000502:physiology; D006893:Hydroxyeicosatetraenoic Acids / Q000494:pharmacology*; D066298:In Vitro Techniques; D009638:Norepinephrine / Q000494:pharmacology; D011817:Rabbits; D014664:Vasodilation / Q000187:drug effects*
D000975:Antioxidants; D006893:Hydroxyeicosatetraenoic Acids; D001205:Ascorbic Acid; D009638:Norepinephrine