title: Hyperoxic and hyperbaric-induced cardioprotection: role of nitric oxide synthase 3.
abstract: OBJECTIVE
  The relative contributions of the fraction of inspired oxygen (FIO2) and atmospheric pressure (ATM) to cardioprotection are unknown. We determined whether the product of FIO2 x ATM (oxygen partial pressure) controls the extent of hyperoxic+hyperbaric-induced cardioprotection and involves activation of nitric oxide synthase (NOS).
  
  
  METHODS
  Adult Sprague Dawley rats (n = 10/gp) were treated for 1 h with (1) normoxia+normobaria (21% O2 at 1 ATM), (2) hyperoxia+normobaria (100% O2 at 1 ATM), (3) normoxia+hyperbaria (21% O2 at 2 ATM) and (4) hyperoxia+hyperbaria (100% O2 at 2 ATM).
  
  
  RESULTS
  Infarct size following 25 min ischemia and 180 min reperfusion was decreased following hyperoxia+normobaria and normoxia+hyperbaria compared with normoxia+normobaria and further decreased following hyperoxia+hyperbaria treatment. l-NAME (200 microM) reversed the cardioprotective effects of hyperoxia+hyperbaria. Nitrite plus nitrate content was increased 2.2-fold in rats treated with normoxia+hyperbaria and hyperoxia+hyperbaria. NOS3 protein increased 1.2-fold and association of hsp90 with NOS3 four-fold in hyperoxic+hyperbaric rats.
  
  
  CONCLUSIONS
  Cardioprotection conferred by hyperoxia+hyperbaria is directly dependent on oxygen availability and mediated by NOS.
authors.affiliation: Division of Pediatric Surgery, Medical College of Wisconsin, Milwaukee, WI 53226, USA. bgcab@yahoo.com
authors.forename: Bernadette P
authors.initials: BP
authors.lastname: Cabigas
authors.forename: Jidong
authors.initials: J
authors.lastname: Su
authors.forename: William
authors.initials: W
authors.lastname: Hutchins
authors.forename: Yang
authors.initials: Y
authors.lastname: Shi
authors.forename: Richard B
authors.initials: RB
authors.lastname: Schaefer
authors.forename: René F
authors.initials: RF
authors.lastname: Recinos
authors.forename: Vani
authors.initials: V
authors.lastname: Nilakantan
authors.forename: Eric
authors.initials: E
authors.lastname: Kindwall
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Niezgoda
authors.forename: John E
authors.initials: JE
authors.lastname: Baker
mesh_terms: D000818:Animals; D004789:Enzyme Activation; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism; D051547:Heme Oxygenase-1 / Q000378:metabolism; D006931:Hyperbaric Oxygenation; D008297:Male; D017202:Myocardial Ischemia / Q000378:metabolism; D015425:Myocardial Reperfusion; D015428:Myocardial Reperfusion Injury / Q000378:metabolism / Q000517:prevention & control*; D009206:Myocardium / Q000737:chemistry*; D009566:Nitrates / Q000032:analysis; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism; D010477:Perfusion; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D018841:HSP90 Heat-Shock Proteins; D009566:Nitrates; D009569:Nitric Oxide; C496314:NOS3 protein, human; D052250:Nitric Oxide Synthase Type III; D051547:Heme Oxygenase-1; D010100:Oxygen