Role of the endothelium in the vascular effects of vitamin C in rats.
The present study was undertaken to determine whether vascular responsiveness and endothelial function were altered in rats after 8 weeks of vitamin C treatment. Thoracic aortae were isolated from control and vitamin C-treated rats and analysed for changes in vascular reactivity. Vitamin C treatment attenuated the contractile response of aortic rings to noradrenaline and KCl. Removal of the endothelium increased the sensitivity of control rings but did not alter the effect of vitamin C. Endothelium-dependent relaxation to acetylcholine was significantly (P<0.05) enhanced by vitamin C, but the endothelium-independent relaxation response to sodium nitroprusside was not affected by vitamin C. The results suggest that the endothelium is not involved in the reduction in vascular sensitivity to contractile agonists caused by vitamin C. In addition, the enhancement of endothelium-dependent relaxation may be due to protection of nitric oxide against inactivation by oxygen free radicals.
Department of Physiology, College of Medicine, University of Lagos, Idi-Araba, PMB 12003, Lagos, Nigeria
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Ettarh
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Sofola
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Adigun