Hyperbaric oxygen therapy aggravates liver reperfusion injury in rats

Abstract

Purpose:To evaluate the effects of hyperbaric oxygen (HO) therapy in the protection against liver ischemia/reperfusion injury. Methods: Thirty-two male Wistar rats were divided into four groups of eight animals each: group A -laparotomy and liver manipulation, group B -liver ischemia and reperfusion, group C -HO pretreatment for 60 min followed by liver ischemia and reperfusion, and group D -pretreatment with ambient air at 2.5 absolute atmospheres for 60 min followed by liver ischemia and reperfusion. Plasma was assayed for aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH). Intra-arterial blood pressure was monitored continuously. Myeloperoxidase activity in the liver and lung was assessed 30 min after reperfusion. Results: Plasma AST, ALT and LDH increased after reperfusion in all animals. Plasma ALT values and myeloperoxidase activity in the liver parenchyma were higher in HO-pretreated animals than in groups A, B and D. HO had a negative hemodynamic effect during liver reperfusion. Conclusion: Liver preconditioning with hyperbaric oxygen therapy aggravated liver ischemia/reperfusion injury in rats as demonstrated by plasma ALT and liver myeloperoxidase activity. Key words: Reperfusion Injury. Liver. Hyperbaric Oxygenation. Rats. RESUMOObjetivo: Avaliar os efeitos da oxigenoterapia hiperbárica (OH) como método preventivo da lesão de isquemia e reperfusão (LIR) do fígado. Métodos: Trinta e dois ratos machos Wistar foram distribuídos em quatro grupos de oito animais cada: Alaparotomia e manipulação hepática, B -isquemia e reperfusão hepática, C -pré-tratamento com OH por 60 minutos seguido de isquemia e reperfusão hepática e D -pré-tratamento com ar ambiente a 2,5 atmosferas absolutas por 60 minuto e isquemia e reperfusão hepática. Dosagens seriadas de AST, ALT e DHL foram realizadas. A pressão intra arterial foi monitorizada continuamente. O grau de infiltração leucocitária no fígado e pulmões foi inferido pela dosagem de mieloperoxidade tecidual. Resultados: O nível sérico de AST, ALT e DHL aumentou em todos animais. Os animais expostos a OH apresentaram níveis de ALT e infiltração leucocitária hepática maior que os demais. A OH apresentou efeitos hemodinâmicos negativos durante a reperfusão hepática. Conclusão: O pré-condicionamento hepático por oxigenoteraia hiperbárica agrava a lesão de isquemia e reperfusão hepática em ratos. Descritores: Traumatismo por Reperfusão. Fígado. Oxigenação Hiperbárica. Ratos

Hyperoxic preconditioning in partial liver ischemia

“…This indicates that the HBO treatment increased the damage to the mitochondrial membrane, because it took longer for it to return to its basal oxygen consumption rate. With regard to serum levels of ALT there was an increase in the results obtained in the I/R group compared to SHAM group (p<0.05), which is in agreement with other studies in the literature 5,8,17 . We also found increased levels of ALT in all groups of HBO treatment, but Pre HBO I/R 30', compared to the I/R group.…”

“…When the groups treated with HBO were compared to the I/R group (not treated), in most of the groups there were no significant differences between values. However, the group Pre HBO I/R 90' showed a significant increase in the state 4 compared to the I/R group, indicating a change in permeability of the mitochondrial inner membrane, responsible for maintaining the proton gradient when the membrane is energized 8 . This indicates that the HBO treatment increased the damage to the mitochondrial membrane, because it took longer for it to return to its basal oxygen consumption rate.…”

“…Therefore, damage caused to the membrane will result in a less efficient oxidative phosphorylation, such as occurs in the reperfusion process, because of an alteration in the membrane permeability and consequent mitochondrial swelling 7 . The effects of the I/R vary from alterations of hepatic enzymes to acute liver failure, depending on its duration 8,9 .…”

Effect of hyperbaric oxygen therapy on liver function during intermittent ischemia

“…Since the mitochondrial membrane are localization sites of the respiratory chain and, and cell membranes are target of the free radicals generated during reperfusion, it is supposed that the destruction of the membranes will result in impairment of oxidative phosphorylation. Thus, the mitochondrial changes are associated with liver microcirculation injury and are good indicators of ischemia and reperfusion 8,[13][14][15] .…”

“…Likewise, serum transaminases quantifications are classic parameters of hepatocellular injury, indicating changes in mitochondrial membrane permeability, and being widely used in studies regarding the ischemia and reperfusion injury 5,13,16,17 .…”