Vitamin C prevents cigarette smoke-induced oxidative damage in vivo

Our recent in vitro results [4] indicate that cigarette smoke induces oxida tion of human plasma proteins and extensive oxidative degradation of the gu inea pig lung, heart, and Liver microsomal proteins, which is almost comple tely prevented by ascorbic acid. In this paper, we substantiate the in vitr o results with in vivo observations. We demonstrate that exposure of subcli nical or marginal vitamin C-deficient guinea pigs to cigarette smoke causes oxidation of plasma proteins as well as extensive oxidative degradation of the lung microsomal proteins. Cigarette smoke exposure also results in som e discernible damage of the heart microsomal proteins. The oxidative damage has been manifested by SDS-PAGE, accumulation of carbonyl and bityrosine, as well as loss of tryptophan and protein thiols. Cigarette smoke exposure also induces peroxidation of microsomal lipids as evidenced by the formatio n of conjugated dienes, malondialdehyde, and fluorescent pigment. Cigarette smoke-induced oxidative damage of proteins and peroxidation of lipids are accompanied by marked drop in the tissue ascorbate levels. Protein damage a nd Lipid peroxidation are also observed in cigarette smoke-exposed pair-fed guinea pigs receiving 5 mg vitamin C/animal/day. However, complete protect ion against protein damage and lipid peroxidation occurs when the guinea pi gs are fed 15 mg vitamin C/animal/day. Also, the cigarette smoke-induced ox idative damage of proteins and lipid is reversed after discontinuation of c igarette smoke exposure accompanied by ascorbate therapy. The results, if e xtrapolated to humans, indicate that comparatively large doses of vitamin C may protect the smokers from cigarette smoke-induced oxidative damage and associated degenerative diseases. (C) 2000 Elsevier Science Inc.