title: Should preconditioning hyperbaric oxygenation protect the liver against ischemia-reperfusion injury? An experimental study in a rat model.
abstract: OBJECTIVE
  We designed studies to test the hypotheses that hyperbaric oxygen (HBO) therapy should protect liver against subsequent ischemia/reperfusion (I/R) injury are scarce and controversial. The purpose of this study was to clarify some questions about the association of HBO with the processes of liver I/R.
  
  
  METHODS
  We divided Wistar rats into 5 groups: (1) SHAM operation, (2) I/R, rats submitted to total pedicle ischemia for 30 minutes followed by 5 minutes of reperfusion; (3) HBO60I/R and (4) HBO120I/R, rats respectively submitted to 60 and 120 minutes of HBO therapy at 2 absolute atmospheres and immediately after submitted to the experimental protocol of I/R; (5) HBO120, rats submitted to 120 minutes of HBO therapy at 2 absolute atmospheres and then immediately after humanely killed. The experimental protocol included (1) serum levels of aspartate and alanine aminotransferase; (2) mitochondrial function; (3) tissue malondialdehyde (MDA); and (4) plasma nitrite/nitrate. Data were analyzed using the Mann-Whitney test and were considered significant P < 5%.
  
  
  RESULTS
  The processes of liver ischemia/reperfusion caused tissue injury with hepatic mitochondrial functional impairment. A single exposure to 120 minutes of HBO caused an increase of tissue MDA. The time of HBO exposure as preconditioning before hepatic I/R is critical in the prevalence of beneficial or deleterious effects. Sixty minutes of hyperoxic preconditioning before liver I/R presents systemic benefits, but no significant tissue preservation. One hundred twenty minutes of hyperoxic preconditioning tissue liver benefits predominate compared with systemic benefits.
  
  
  CONCLUSIONS
  The HBO preconditioning therapeutic benefits to liver I/R injury are time dependent, suggesting a therapeutic window that needs to be clearly defined in future studies.
authors: Faculty of Medicine of Marília (FAMEMA), Marilia-SP, Brazil.
authors: D M
authors: DM
authors: Losada
authors: Faculty of Medicine of Ribeirão Preto, University of São Paulo (FMRP-USP), Ribeirão Preto-SP, Brazil.
authors: M E
authors: ME
authors: Jordani
authors: Faculty of Medicine of Ribeirão Preto, University of São Paulo (FMRP-USP), Ribeirão Preto-SP, Brazil.
authors: M C
authors: MC
authors: Jordani
authors: Faculty of Medicine of Ribeirão Preto, University of São Paulo (FMRP-USP), Ribeirão Preto-SP, Brazil.
authors: M A N C
authors: MA
authors: Piccinato
authors: Faculty of Medicine of Ribeirão Preto, University of São Paulo (FMRP-USP), Ribeirão Preto-SP, Brazil.
authors: C F
authors: CF
authors: Fina
authors: Faculty of Medicine of Ribeirão Preto, University of São Paulo (FMRP-USP), Ribeirão Preto-SP, Brazil.
authors: O
authors: O
authors: Feres
authors: Faculty of Medicine of Marília (FAMEMA), Marilia-SP, Brazil.
authors: A B
authors: AB
authors: Chies
authors: Faculty of Medicine of Ribeirão Preto, University of São Paulo (FMRP-USP), Ribeirão Preto-SP, Brazil.
authors: P R B
authors: PR
authors: Evora
authors: Faculty of Medicine of Marília (FAMEMA), Marilia-SP, Brazil. Electronic address: orlando@fmrp.usp.br.
authors: O
authors: O
authors: de Castro E Silva
mesh_terms: D000410:Alanine Transaminase / Q000097:blood; D000818:Animals; D001224:Aspartic Acid / Q000097:blood; D004195:Disease Models, Animal; D005609:Free Radicals; D006931:Hyperbaric Oxygenation / Q000379:methods*; D018496:Hyperoxia; D019194:Ischemic Preconditioning / Q000379:methods*; D008099:Liver / Q000503:physiopathology; D008297:Male; D008315:Malondialdehyde / Q000737:chemistry; D008928:Mitochondria / Q000378:metabolism / Q000473:pathology; D009566:Nitrates / Q000097:blood; D009573:Nitrites / Q000097:blood; D010100:Oxygen / Q000378:metabolism*; D010101:Oxygen Consumption; D051381:Rats; D017208:Rats, Wistar; D015427:Reperfusion Injury / Q000473:pathology* / Q000503:physiopathology* / Q000517:prevention & control*; D013997:Time Factors
chemical_list: D005609:Free Radicals; D009566:Nitrates; D009573:Nitrites; D001224:Aspartic Acid; D008315:Malondialdehyde; D000410:Alanine Transaminase; D010100:Oxygen