title: Heavy and light cigarette smokers have similar dysfunction of endothelial vasoregulatory activity: an in vivo and in vitro correlation.
abstract: OBJECTIVE
  The goal of this study was to investigate the dose-dependent effects of active cigarette smoking on endothelial nitric oxide (NO) and endothelin-1 (ET-1) biosynthesis.
  
  
  BACKGROUND
  Limited studies have suggested that active cigarette smoking may be associated with a dose-dependent reduction of endothelium-dependent vasodilation (EDV). The underlying biochemical changes that cause this dose-specific effect, such as changes in the endothelial NO biosynthetic pathway and ET-1 production, have not been examined.
  
  
  METHODS
  Flow- and nitroglycerin-mediated reactivity of the brachial artery were measured in eight nonsmokers, seven light smokers (< or =1 pack/week) and eight heavy smokers (> or =1 pack/day), and their sera were added to confluent ( approximately 85%) monolayers of human umbilical endothelial cells (HUVECs) for 12 h. Basal and substance P-stimulated NO and basal ET-1 production were measured. The HUVECs used for measuring basal NO production were lysed, and both endothelial NO synthase (eNOS) protein expression and eNOS activity were determined.
  
  
  RESULTS
  Serum cotinine level and pack-years of smoking were significantly lower in light smokers compared with heavy smokers (p < 0.006 and p < 0.004, respectively). There were no significant differences between heavy smokers and light smokers in EDV (p = 0.52), basal- (p = 0.70) and stimulated-NO production (p = 0.95), eNOS protein (p = 0.40) and eNOS activity (p = 0.63). Compared with nonsmokers, all the parameters were significantly altered in both of the smokers' groups. No differences were found in nitroglycerin-mediated vasodilation and in vitro ET-1 production among the three groups.
  
  
  CONCLUSIONS
  These results indicate light smoking may have similar detrimental effects on EDV and NO biosynthetic pathway as does heavy smoking. These data may have important implications concerning the amount of active cigarette exposure that imparts cardiovascular risk.
authors.affiliation: Department of Medicine, the Comprehensive Cardiovascular Center, Saint Vincent Catholic Medical Centers of New York, 170 West 12th Street, New York, NY 10011, USA.
authors.forename: Rajat S
authors.initials: RS
authors.lastname: Barua
authors.forename: John A
authors.initials: JA
authors.lastname: Ambrose
authors.forename: Lesley-Jane
authors.initials: LJ
authors.lastname: Eales-Reynolds
authors.forename: Mary C
authors.initials: MC
authors.lastname: DeVoe
authors.forename: John G
authors.initials: JG
authors.lastname: Zervas
authors.forename: Dhanonjoy C
authors.initials: DC
authors.lastname: Saha
mesh_terms: D001916:Brachial Artery / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D019332:Endothelin-1 / Q000096:biosynthesis*; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism; D006801:Humans; D008297:Male; D009569:Nitric Oxide / Q000096:biosynthesis*; D012907:Smoking / Q000378:metabolism*; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D019332:Endothelin-1; D009569:Nitric Oxide