title: Augmented oxidative stress of platelets in chronic smokers. Mechanisms of impaired platelet-derived nitric oxide bioactivity and augmented platelet aggregability.
abstract: OBJECTIVE
  We investigated whether impaired platelet-derived nitric oxide (PDNO) bioactivity and augmented platelet aggregability in chronic smokers are related to the imbalance of the intraplatelet redox state through increased oxidative stress.
  
  
  BACKGROUND
  Chronic smoking impairs PDNO release and augments platelet aggregability. However, their mechanisms are unknown.
  
  
  METHODS
  Collagen-induced PDNO release, platelet aggregation, plasma and intraplatelet vitamin C and reduced glutathione (GSH), intraplatelet cyclic guanosine 3',5'-monophosphate (cGMP) and intraplatelet nitrotyrosine production, which is a marker of the peroxynitrite formation, were measured in 11 chronic smokers and 10 age-matched nonsmokers.
  
  
  RESULTS
  Release of PDNO and levels of intraplatelet cGMP were lower, and platelet aggregation was greater, in smokers than in nonsmokers. Intraplatelet vitamin C and GSH levels were lower in smokers than in nonsmokers. Intraplatelet nitrotyrosine production was greater in smokers than in nonsmokers. Next, we investigated the effects of oral vitamin C administration (2 g). After vitamin C administration, intraplatelet vitamin C levels were increased and not different at 2 h between the two groups. Then, PDNO release, intraplatelet cGMP levels and platelet aggregation in smokers were restored to the levels of nonsmokers. In smokers, PDNO release and consumption of GSH during platelet aggregation were inversely correlated, and consumption was much less after vitamin C administration. Vitamin C administration decreased intraplatelet nitrotyrosine production in smokers.
  
  
  CONCLUSIONS
  Impaired PDNO bioactivity and augmented platelet aggregability may be caused by an imbalance of the intraplatelet redox state through increased oxidative stress in smokers.
authors.affiliation: Department of Internal Medicine III and Cardiovascular Research Institute, Kurume University School of Medicine, Kurume, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Takajo
authors.forename: H
authors.initials: H
authors.lastname: Ikeda
authors.forename: N
authors.initials: N
authors.lastname: Haramaki
authors.forename: T
authors.initials: T
authors.lastname: Murohara
authors.forename: T
authors.initials: T
authors.lastname: Imaizumi
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000975:Antioxidants / Q000032:analysis / Q000378:metabolism / Q000627:therapeutic use; D001205:Ascorbic Acid / Q000032:analysis / Q000097:blood / Q000502:physiology / Q000627:therapeutic use; D001682:Biological Availability; D001792:Blood Platelets / Q000737:chemistry* / Q000378:metabolism*; D016022:Case-Control Studies; D002908:Chronic Disease; D006152:Cyclic GMP / Q000032:analysis / Q000378:metabolism; D016166:Free Radical Scavengers / Q000032:analysis / Q000378:metabolism / Q000627:therapeutic use; D005978:Glutathione / Q000032:analysis / Q000097:blood; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000032:analysis* / Q000378:metabolism*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D030421:Peroxynitrous Acid / Q000096:biosynthesis / Q000378:metabolism; D010974:Platelet Aggregation; D012907:Smoking / Q000188:drug therapy / Q000378:metabolism*; D013997:Time Factors; D014443:Tyrosine / Q000031:analogs & derivatives* / Q000032:analysis / Q000378:metabolism
chemical_list: D000975:Antioxidants; D016166:Free Radical Scavengers; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; C002744:3-nitrotyrosine; D014443:Tyrosine; D005978:Glutathione; D006152:Cyclic GMP; D001205:Ascorbic Acid