Adverse Effects of Cigarette Smoke on NO Bioavailability

Abstract

Abstract-Endothelial dysfunction is a hallmark of cardiovascular disease, and the L-arginine:NO pathway plays a critical role in determining endothelial function. Recent studies suggest that smoking, a well-recognized risk factor for vascular disease, may interfere with L-arginine and NO metabolism; however, this remains poorly characterized. Accordingly, we performed a series of complementary in vivo and in vitro studies to elucidate the mechanism by which cigarette smoke adversely affects endothelial function. In current smokers, plasma levels of asymmetrical dimethyl-arginine (ADMA) were 80% higher (Pϭ0.01) than nonsmokers, whereas citrulline (17%; PϽ0.05) and N-hydroxy-L-arginine (34%; PϽ0.05) were significantly lower. Exposure to 10% cigarette smoke extract (CSE) significantly affected endothelial arginine metabolism with reductions in the intracellular content of citrulline (81%), N-hydroxy-L-arginine (57%), and arginine (23%), while increasing ADMA (129%). CSE significantly inhibited (38%) arginine uptake in conjunction with a 34% reduction in expression of the arginine transporter, CAT1. In conjunction with these studies, CSE significantly reduced the activity of eNOS and NO production by endothelial cells, while stimulating the production of reactive oxygen species. In conclusion, cigarette smoke adversely affects the endothelial L-arginine NO synthase pathway, resulting in reducing NO production and elevated oxidative stress. In conjunction, exposure to cigarette smoke increases ADMA concentration, the latter being a risk factor for cardiovascular disease. Key Words: smoking Ⅲ endothelium Ⅲ metabolism A therosclerotic coronary and cerebrovascular disease are leading causes of death and disability in the Western world, and cigarette smoking has been clearly identified as a risk factor for coronary artery disease (reviewed by Ambrose and Barua 1 ). In this context, measures of endothelial function have been associated with cardiovascular outcome, 2 and smoking has been widely associated with reduced endothelial function. 3 The endothelium plays a central role in the modulation of vascular tone, the inhibition of platelet aggregation and vascular smooth muscle proliferation, and a key participation in angiogenesis under appropriate conditions. NO is well recognized as playing a pivotal part in these endothelial properties, being produced by the endothelial isoform of NO from its preferred substrate L-arginine. In this context, provision of sufficient L-arginine is critical for the sustained production of NO supply, 4 mediated in endothelial cells (ECs) principally by the type 1 cationic amino acid transporter (CAT1). Previous studies indicate that deleterious actions of cigarette smoke on endothelial function could be mitigated by supplemental L-arginine; 5 however, to date, the precise basis for this interaction remains unclear. One explanation is that cigarette smoke exerts an inhibitory effect on components of the L-arginine:NO pathway to influence NO production. In addition, potential effects of cigar...

Effect of supplementation with B vitamins and antioxidants on levels of asymmetric dimethylarginine (ADMA) and C-reactive protein (CRP): a double-blind, randomised, factorial design, placebo-controlled trial

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“…[23][24][25][26][27] In the present study, the treatment characteristics and lifestyles of patients were similar, excluding the possible effects of confounding factors on these results.…”

Improvement in blood pressure after short-term inorganic nitrate supplementation is attenuated in cigarette smokers compared to non-smoking controls

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