title: Redox-dependent increases in glutathione reductase and exercise preconditioning: role of NADPH oxidase and mitochondria.
abstract: OBJECTIVE
  We have previously shown that exercise leads to sustainable cardioprotection through a mechanism involving improved glutathione replenishment. This study was conducted to determine if redox-dependent modifications in glutathione reductase (GR) were involved in exercise cardioprotection. Furthermore, we sought to determine if reactive oxygen species generated by NADPH oxidase and/or mitochondria during exercise were triggering events for GR modulations.
  
  
  RESULTS
  Rats were exercised for 10 consecutive days, after which isolated hearts were exposed to ischaemia/reperfusion (25 min/120 min). Exercise protected against infarction and arrhythmia, and preserved coronary flow. The GR inhibitor BCNU abolished the beneficial effects. GR activity was increased following exercise in a redox-dependent manner, with no change in GR protein levels. Because fluorescent labelling of GR protein thiols showed lower amounts of reduced thiols after exercise, we sought to determine the source of intracellular reactive oxygen species that may be activating GR. Subsets of animals were exercised immediately after treatment with either NADPH-oxidase inhibitors apocynin or Vas2870, or with mitoTEMPO or Bendavia, which reduce mitochondrial reactive oxygen species levels. The cardioprotective effects of exercise were abolished if animals exercised in the presence of NADPH oxidase inhibitors, in clear contrast to the mitochondrial reagents. These changes correlated with thiol-dependent modifications of GR.
  
  
  CONCLUSIONS
  Adaptive cardioprotective signalling is triggered by reactive oxygen species from NADPH oxidase, and leads to improved glutathione replenishment through redox-dependent modifications in GR.
authors: Department of Physiology, Brody 6N-98, 600 Moye Blvd, Brody School of Medicine, East Carolina University, Greenville, NC 27834, USA.
authors: Chad R
authors: CR
authors: Frasier
authors: Fatiha
authors: F
authors: Moukdar
authors: Hetal D
authors: HD
authors: Patel
authors: Ruben C
authors: RC
authors: Sloan
authors: Luke M
authors: LM
authors: Stewart
authors: Rick J
authors: RJ
authors: Alleman
authors: Justin D
authors: JD
authors: La Favor
authors: David A
authors: DA
authors: Brown
mesh_terms: D000818:Animals; D005260:Female; D005978:Glutathione / Q000378:metabolism; D005980:Glutathione Reductase / Q000502:physiology*; D008928:Mitochondria / Q000502:physiology*; D015428:Myocardial Reperfusion Injury / Q000209:etiology; D019255:NADPH Oxidases / Q000502:physiology*; D010084:Oxidation-Reduction; D010805:Physical Conditioning, Animal; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D017382:Reactive Oxygen Species; D019255:NADPH Oxidases; D005980:Glutathione Reductase; D005978:Glutathione