Effect of hyperbaric oxygen therapy on liver function during intermittent ischemia

Abstract

PURPOSE:To analyze the effects of hyperbaric oxygen therapy on liver function in rats previously subjected to ischemia and reperfusion. METHODS: A randomly distribution of 23 Wistar rats was conducted into three groups: SHAM, animals subjected to surgical stress without restricting blood flow by clamping the hepatic pedicle, IR, rats underwent hepatic vascular occlusion intermittently for two complete cycles of 15 minutes of ischemia followed by 5 min of reperfusion, IR / HBO, rats underwent hepatic pedicle clamping and thereafter exposed to hyperbaric oxygen pressure of 2 absolute atmospheres for 60 minutes. We evaluated liver function through mitochondrial function, determined by the stages 3 and 4 of respiration, respiratory control ratio (RCR) and mitochondrial permeability transition (Swelling). Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were also quantified . We analyzed the results using the Mann-Whitney test and were considered significant all results with p <0.05. RESULTS: There were significant differences between the results of stage 3 in SHAM vs IR group ; of the stage 4 in the groups IR vs SHAM and SHAM vs IR /HBO; of the Respiratory Control Ratio (RCR) in the group IR vs IR / HBO ; of alanine aminotransferase in the groups IR vs SHAM , SHAM vs IR/HBO and IR vs IR / HBO; aspartate aminotransferase in the groups SHAM vs IR and SHAM vs IR / HBO. CONCLUSION: The whole analysis of the mitochondiral function indicators permits us to conclude that the hyperbaric oxygen therapy acted as a protective agent of the mitochondrial function, minimizing the ischemia-reperfusion injury of the hepatic parenchyma. Key words: Hyperbaric Oxygen Therapy. Mitochondria. Liver Ischemia. Reperfusion. RESUMO OBJETIVO:Analisar os efeitos da oxigenoterapia hiperbárica sobre a função hepática de ratos previamente submetidos à isquemia e reperfusão. MÉTODOS: Realizou-se a distribuição aleatória de 23 ratos Wistar em três grupos: SHAM, animais submetidos ao estresse cirúrgico sem restrição de fluxo sanguíneo por clampeamento do pedículo hepático; IR ratos submetidos a oclusão vascular hepática de maneira intermitente em dois ciclos completos de 15 minutos de isquemia, seguidos por 5 min de reperfusão; IR/HBO, ratos submetidos ao clampeamento do pedículo hepático e ,ulteriormente , expostos a oxigenoterapia hiperbárica a pressão de 2 atmosferas absolutas durante 60 minutos. Avaliou-se a função hepática através da função mitocondrial, determinada pelos estados 3 e 4 da respiração mitocondrial, razão de controle respiratório(RCR) e transição de permeabilidade mitocondrial (Swelling) .Quantificou-se também alanina aminotransferase e aspartato aminotransferase séricas. Analisou-se os resultados pelo teste de Mann-Whitney e foram considerados significativos os valores de p < 0,05. RESULTADOS:Houve diferença significativa nos valores do estado 3 no grupo SHAM vs IR; estado 4 nos grupos SHAM vs IR, SHAM vsIR/HBO; Razão de Controle Respiratório(RCR) no grupo IR vs IR/HBO; alanina aminotransferase n...

Effects of hyperbaric oxygen therapy on the liver after injury caused by the hepatic ischemia-reperfusion process

“…Although expected, no difference was observed with HBO. This fact was not observed in other studies, in which the SHAM and IR groups already presented some difference [10][11][12]16 . In those studies there was an increase in the rate of oxygen consumption by the mitochondria compared to the SHAM group in order to maintain the electrochemical proton gradient on the mitochondrial membrane so that the membrane would be able to phosphorylate ADP 16,17 .…”

Effect of hyperbaric hepatic hyperoxia on the liver of rats submitted to intermittent ischemia/reperfusion injury

“…In the present study, with respect to MDA, we observed a tendency to an increase of ROS in the I/R group, which was aggravated in the HBO-I/R group, demonstrating a lack of protection, as also reported in other studies 9,10,19 .…”

“…No significant improvement occurred in AST levels, with no significant difference between the groups submitted or not to HBO, and with the levels of both groups being higher than those of the control group. This leads us to question the hepatoprotective effect of hyperoxic preconditioning, which is supported by some authors and contested by others 9,10,19,20 .…”

Hyperoxic preconditioning in partial liver ischemia

“…This result is found by other authors 12,13 , but in different models of ischemia-reperfusion. Taking into consideration the oxygen consumption in stage 3 it was not found in our study significant difference between the group that underwent ischemia and, reperfusion with or without exposure to HBO, demonstrating that HBO was not harmful when this parameter was evaluated.…”

“…The use of HBO in the I/R damage is controverse, because it was believed that its use would increase tissue damage by raising the level of oxygen and consequently the level of reactive species and free radicals in the blood. However, there are studies that show positive changes caused by its use, suggesting a protective effect in different tissues [10][11][12] .…”