title: Vitamin C has no effect on endothelium-dependent vasomotion and acute endogenous fibrinolysis in healthy smokers.
abstract: Blood flow and plasma fibrinolytic factors were measured on five occasions in both forearms of eight otherwise healthy male smokers during unilateral brachial artery infusion of the endothelium-dependent vasodilator, substance P (2 to 8 pmol/min), and the endothelium-independent vasodilator, sodium nitroprusside (2 to 8 microg/min). On the first occasion, intra-arterial vitamin C was co-infused at 25 mg/min. On subsequent occasions, subjects attended after 28 and 35 days treatment with oral vitamin C (1 g daily) or placebo in a double-blind randomized crossover design still smoking but with and without acute smoke inhalation (3 cigarettes over 30 minutes). Basal plasma ascorbate concentrations increased from 37 +/- 6 micromol/L to 105 +/- 11 micromol/L following oral vitamin C supplementation (P = 0.002). Substance P caused dose-dependent increases in forearm blood flow (P < 0.001, ANOVA) and t-PA release (P < 0.05, ANOVA) that was unaffected by acute recent smoke inhalation, intra-arterial vitamin C, or oral vitamin C administration (p = ns). Likewise there were no effects on sodium nitroprusside-induced vasodilatation (p = ns). Neither acute local intra-arterial nor prolonged oral vitamin C supplementation reverses smoking-related endothelial dysfunction and impaired endogenous t-PA release. We conclude that the adverse vascular actions of smoking are not principally mediated through oxidative stress.
authors.affiliation: Clinical Pharmacology Unit and Research Centre, University of Edinburgh, Western General Hospital, Edinburgh, UK.
authors.forename: M Paola
authors.initials: MP
authors.lastname: Pellegrini
authors.forename: David E
authors.initials: DE
authors.lastname: Newby
authors.forename: Neil R
authors.initials: NR
authors.lastname: Johnston
authors.forename: Simon
authors.initials: S
authors.lastname: Maxwell
authors.forename: David J
authors.initials: DJ
authors.lastname: Webb
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000097:blood / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004730:Endothelium, Vascular / Q000187:drug effects; D005342:Fibrinolysis / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D009599:Nitroprusside / Q000494:pharmacology*; D012907:Smoking / Q000378:metabolism*; D013373:Substance P / Q000494:pharmacology*; D010959:Tissue Plasminogen Activator / Q000187:drug effects*; D014664:Vasodilation / Q000187:drug effects; D014665:Vasodilator Agents / Q000494:pharmacology*
chemical_list: D000975:Antioxidants; D014665:Vasodilator Agents; D009599:Nitroprusside; D013373:Substance P; D010959:Tissue Plasminogen Activator; D001205:Ascorbic Acid