Efeitos da administração aguda de vitamina C na reatividade vascular arterial e venosa em tabagistas

AUTOR(ES)
DATA DE PUBLICAÇÃO

2003

RESUMO

Background: Chronic smoking is associated with endothelial dysfunction. Vitamin c, an antioxidant, improves the endothelium-mediated vasodilatation in arteries in smokers. There is significant heterogeneity of endothelial function within the circulation. Since veins are generally not susceptible to atherosclerosis, this model allows comparable assessment of changes in endothelial function between both territories. Methods and Results: We studied 06 healthy non-smokers and 07 healthy moderate smokers with the dorsal hand vein compliance technique and the flow mediated dilation. Dose response curves to bradykinin (BK) and sodium nitroprusside (SNP) were constructed to test the endothelium-dependent and non-dependent relaxation before and after acute infusion of vitamin C (25mg/min). Smokers had an impaired vasodilatation to bradykinin compared to non-smokers (Emax = 95,7 ? 21,2% vs 71,2 ? 17,3%; respectively, p<0,05). Vitamin C administration in dorsal hand vein significantly increased the vasodilatation to bradykinin in smokers (Emax = 71,2 ? 17,3% vs 88,3 ? 7,0%; p<0,05) but not in non-smokers (Emax = 95,7 ? 21,2% vs 82,7 ? 4,1%; non significant). Similarly, the arterial response in smokers had an impaired endothelium-dependent dilatation compared to non-smokers (16,2 ± 2,7% vs 8,5 ± 3,7%; respectively, p<0,05) and vitamin C restored this response in smokers (8,5 ± 3,7% vs 17,7 ± 7,7%; p<0,05) but not in non-smokers (16,2 ± 2,7% vs 14,4 ± 4,1%; non significant). The endothelium non-dependent dilatation did not differ in the studied groups. Conclusions: Smokers had similar impaired endothelium-dependent vasodilatation responsiveness in both vascular beds. Vitamin c restores the impaired endothelium-dependent responsiveness in smokers

ASSUNTO(S)

vitamina c vasodilatação endotelio fumo - vicio

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