title: High glucose sensitizes adult cardiomyocytes to ischaemia/reperfusion injury through nitrative thioredoxin inactivation.
abstract: OBJECTIVE
  Ischaemic cardiac injury is significantly increased in diabetic patients, but its underlying mechanisms remain incompletely understood. The current study attempted to identify new molecular mechanisms potentially contributive to hyperglycaemic-exaggeration of myocardial ischaemic injury.
  
  
  RESULTS
  Adult mouse cardiomyocytes were cultured in normal-glucose (NG, 5.5 mM) or high-glucose (HG, 25 mM) medium. Twelve hours after NG or HG pre-culture, cardiomyocytes were subjected to 3 h of simulated ischaemia (SI), followed by 3 h of reperfusion (R) in NG medium. Prior to and after SI/R, the following were determined: cardiomyocyte death and apoptosis, sustained oxidative/nitrative stress and thioredoxin (Trx) activity, expression, and nitration. Compared with NG-cultured cardiomyocytes, 12 h HG culture significantly increased superoxide and peroxynitrite production, increased Trx-1 nitration, and reduced Trx activity (P < 0.01). Despite being subject to identical SI/R procedures and conditions, cells pre-cultured in HG sustained greater injury, evidenced by elevated lactate dehydrogenase release and caspase-3 activation (P < 0.01). Moreover, SI/R induced greater superoxide/peroxynitrite overproduction and greater Trx-1 nitration and inactivation in HG pre-cultured cardiomyocytes than in NG pre-cultured cardiomyocytes. Finally, the supplementation of human Trx-1, superoxide scavenger, or peroxynitrite decomposition catalyst in HG pre-cultured cells reduced Trx-1 nitration, preserved Trx-1 activity, and normalized SI/R injury to levels observed in NG pre-cultured cardiomyocytes.
  
  
  CONCLUSIONS
  High glucose sensitized cardiomyocytes to ischaemia/reperfusion injury through nitrative Trx-1 inactivation. Interventions restoring Trx-1 activity in the diabetic heart may represent novel therapies attenuating cardiac injury in diabetic patients.
authors.affiliation: Department of Cardiology, Xijing Hospital, The Fourth Military Medical University, 15 West Changle Road, Xian 710032, China.
authors.forename: Ronghua
authors.initials: R
authors.lastname: Luan
authors.forename: Shaowei
authors.initials: S
authors.lastname: Liu
authors.forename: Tao
authors.initials: T
authors.lastname: Yin
authors.forename: Wayne Bond
authors.initials: WB
authors.lastname: Lau
authors.forename: Qiong
authors.initials: Q
authors.lastname: Wang
authors.forename: Wenyi
authors.initials: W
authors.lastname: Guo
authors.forename: Haichang
authors.initials: H
authors.lastname: Wang
authors.forename: Ling
authors.initials: L
authors.lastname: Tao
mesh_terms: D000818:Animals; D017209:Apoptosis; D053148:Caspase 3 / Q000378:metabolism; D002470:Cell Survival; D002478:Cells, Cultured; D048909:Diabetes Complications / Q000378:metabolism* / Q000473:pathology; D005947:Glucose / Q000378:metabolism*; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D015428:Myocardial Reperfusion Injury / Q000378:metabolism* / Q000473:pathology; D032383:Myocytes, Cardiac / Q000201:enzymology / Q000378:metabolism* / Q000473:pathology; D019255:NADPH Oxidases / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D018384:Oxidative Stress; D030421:Peroxynitrous Acid / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D013879:Thioredoxins / Q000378:metabolism*
chemical_list: C515559:Txn1 protein, mouse; D013481:Superoxides; D030421:Peroxynitrous Acid; D013879:Thioredoxins; D007770:L-Lactate Dehydrogenase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D019255:NADPH Oxidases; C505409:Casp3 protein, mouse; D053148:Caspase 3; D005947:Glucose