The Mechanism Of Hepatic Artery Hypoxic Injury And Hyperbaric Oxygen Therapy As Well As The Clinic Observation

Objective: The present study was conducted to (1) observe the change of liver blood flower and pathology, (2) investigate the role of hypoxia inducible factor-1α (HIF-1α) gene expression and HIF-1α protein expression in hepatic artery hypoxic liver injury, (3) study the effect of p53 protein expression and hepatocyte apoptosis on hypoxic liver injury, (4) clarify the role of inducible nitric oxide (iNOS) gene expression, iNOS and nitric oxide (NO) in hypoxic liver injury, (5) evaluate the protectiver role of hyperbaric oxygen (HBO) in liver hypoxic injury caused by hepatic artery ligation (HAL), and (6) to observe the therapic effect of HBO on hepatic artery thrombosis after liver transplantation. Material and methods: 96 male SD rats were randomly divided into three groups as follows: control group, HAL group and HBO group. Liver were subjected to skeletonization and perfused with cold ringer's solution (with heparin 20U/ml) in each group. HAL were performed in HAL and HBO group. HBO treatments were performed twice daily for 60 minutes at 2.5atm absolute in HBO group two hours after operation. Tissue specimens from liver and systemic blood sample were obtained. The study consisted of examination for liver blood flower, iNOS, NO, ALT, immunohistochemical staining, the reverse transcription polymerase chain reaction on HIF-la and iNOS messenger ribonucleic acid expression, terminal deoxynucleotidyl transferase mediated dUTP-rhodamine nick end labeling assay of hepatocyte apoptosis. Four patients who developed HAT after liver transplantation were treated with HBO therapy. Primary outcome measures were liver function and imaging.Results: 1. HAL caused a 22% reduction in liver blood flower (p<0.01 vs control). 14 day Post operation, there were no difference in liver blood flower from the HBO and from the control group, whereas the liver blood flower in the HBOgroup were significantly increase compared with that in the HAL group(4.22 ± 0.31V vs 3.62 ± 0.49V). 2. HAL group Liver HIF-1 a mRNA expression and HIF-1 a protein labeling index were significantly increased compared with control group. HIF-1 a p53 positive hepatocytes were around the centrilobular vein. Maximal liver HIF-1 a mRNA expression and HIF-1 a protein labeling index was significantly lower in HBO group than in HAL group(p<0.05). 3. Liver p53 labeling index was higher in HAL group than in control and HBO group. p53 positive hepatocytes were also around the centrilobular vein. Meanwhile, Liver p53 labeling index was higher in HBO group than in control group. 4. Maximal liver iNOS mRNA expression was higher in HAL group than in control group. Plasma and tissue (liver) iNOS and NO levels increased markedly in HAL group than in control group. HBO treatments could significantly decrease iNOS mRNA expression, reduce plasma and tissue iNOS levels. 5. Apoptosis index and serum ALT were higher in HAL group than in control and in HBO group. 6. Two of the four HAT patients who were treated with HBO therapy has remained clinically well and has no evidence hepatic abscess, with follow-up one year. The other two patients improved clinically and biologically after HBO therapy. Conclusion: 1. Our data suggest that liver hypoxia can trigger HIF-1 a gene expression and accumulation of HIF-1 a p53 protein, particularly in the centrilober hepatocyte. By binding with p53, HIF-1 a can lead to hepatocyte apoptosis. iNOS is one of the HIF-1 a target gene. Accumulation of HIF-1 a in liver up-regulates iNOS gene expression, which would enhance synthesis and release of iNOS and NO. High level of NO has harmful effect to hepatocyte. HBO treatment improves liver perfusion, reduces expressions of HIF-1 a and apoptotic gene p53, inhibit of heptocyte apoptosis. Meanwhile, HBO down-regulates iNOS gene expression, reduces synthesis of iNOS and NO. This result indicates that HBO has multiple liver protective functions after hepatic artery ligation. 2. This study also suggests HBO may diminish the risk for hepatic necrosis and bile duct complication which were caused by HAT. HBO cooperation with other therapy has a good effect on hepatic abscess. We suggest that HBO, assuring oxygen supplementation via the portal blood supply, was helpful in hepatectomy under hepatic total vascular exclusion and HAT after liver transplantation.