Preserved mitochondrial function by allopurinol despite deteriorated hemodynamics in warm ischemia-damaged canine liver

Study of rat hepatocytes in primary culture submitted to hypoxia and reoxygenation: action of the cytoprotectors prostaglandin E1, superoxide dismutase, allopurinol and verapamil

CONTEXT: Exposure of hepatocytes to pathological conditions in a microenvironment of hypoxia and reoxygenation is very frequent in hepatic diseases. Several substances present perspectives for cytoprotective action on hepatocyte submitted to reoxygenation after hypoxia and simple hypoxia. OBJECTIVE: We research therapeutic options for hepatocytes submitted to hypoxia and hypoxia + reoxygenation injury. METHODS: Primary culture of rat hepatocytes was submitted to hypoxia (2 hours) plus reoxygenation (2 hours) and simple hypoxia (4 hours) in the presence or the absence of cytoprotectors. The hepatocyte lesion was evaluated by functional criteria through percentage of lactate dehydrogenase released and cell viability. The effects of the cytoprotectors prostaglandin E1 3 ηg/mL, superoxide dismutase 80 μg/mL, allopurinol 20 μM and verapamil 10-4 M were studied in this model of injury. RESULTS: Reoxygenation after hypoxia induced more significant lesion in cultured hepatocytes compared to simple hypoxia, detected by analysis of functional criteria. There was a significant reduction of percentage of lactate dehydrogenase released and a significant increase of percentage of cell viability in the hypoxia + reoxygenation + cytoprotectors groups compared to hypoxia + reoxygenation groups. Prostaglandin E1, superoxide dismutase and verapamil also protected the group submitted to simple hypoxia, when evaluated by functional criteria. CONCLUSIONS: We conclude that reoxygenation after hypoxia significantly increased the lesion of cultured rat hepatocytes when compared to simple hypoxia. Prostaglandin E1, superoxide dismutase, allopurinol and verapamil acted as cytoprotectors to the rat cultured hepatocytes submitted to hypoxia + reoxygenation in vitro. The substances prostaglandin E1, superoxide dismutase and verapamil protected hepatocytes submitted to simple hypoxia on the basis of all the criteria studied in this experimental model.

Comparison of various lazaroid compounds for protection against ischemic liver injury

Lazaroids are a group of 21-aminosteroids that lack steroid action but have a potent cytoprotective effect by inhibiting iron-dependent lipid peroxidation. However, there have been conflicting reports on the effectiveness and potency of the various lazaroid compounds. In this study, we compared the effectiveness of three major lazaroids on warm liver ischemia in dogs using a 2-hr hepatic vascular exclusion model. The agents were given to the animals intravenously for 30 min before ischemia. The animals were divided into 5 groups: Control (n=10), no treatment; Group F (n=6), U-74006F (10 mg/kg); Group G (n=6), U-74389G (10 mg/kg); Group A1 (n=6), U-74500A (10 mg/kg); Group A2 (n=6), U-74500A (5 mg/kg). The effect of treatment was evaluated by two-week animal survival, hepatic tissue blood flow, liver function tests, blood and tissue biochemistry, and histological analyses. Animal survival in all treated groups was significantly improved compared with the control (83-100% versus 30%). Elevation of liver enzymes after reperfusion was markedly attenuated in treated groups, except for an early significant increase in Group G. Postreperfusion hepatic tissue blood flow was much higher in all treated animals (50% of the preischemic level vs. 25% in the control). Lazaroids, particularly U-74500A at 5 mg/kg (Group A2), suppressed adenine nucleotide degradation during ischemia and enhanced the resynthesis of high-energy phosphates after reperfusion. Although structural abnormalities in postreperfusion liver tissues were markedly ameliorated in all treated groups, Group A2 showed significantly less neutrophil infiltration. Liver injury from warm ischemia and reperfusion was attenuated with all lazaroid compounds, of which U-74500A at 5 mg/kg exhibited the most significant protective activity.

Comparison of various lazaroid compounds for protection against ischemic liver injury

Lazaroids are a group of 21 -aminosteroids that lack steroid action but have a potent cytoprotective effect by inhibiting iron-dependent lipid peroxidation. However, there have been conflicting reports on the effectiveness and potency of the various lazaroid compounds. In this study, we compared the effectiveness of three major lazaroids on warm liver ischemia in dogs using a 2-hr hepatic vascular exclusion model. The agents were given to the animals intravenously for 30 min before ischemia. The animals were divided into 5 groups: Control (n=10), no treatment; Group F (n=6), U-74006F (10 mg/kg); Group G (n=6), U-74389G (10 mg/kg); Group A1 (n=6), U-74500A (10 mg/kg); Group A2 (n=6), U-74500A (5 mg/kg). The effect of treatment was evaluated by two-week animal survival, hepatic tissue blood flow, liver function tests, blood and tissue biochemistry, and histological analyses. Animal survival in all treated groups was significantly improved compared with the control (83–100% versus 30%). Elevation of liver enzymes after reperfusion was markedly attenuated in treated groups, except for an early significant increase in Group G. Postreperfusion hepatic tissue blood flow was much higher in all treated animals (50% of the preischemic level vs. 25% in the control). Lazaroids, particularly U-74500A at 5 mg/kg (Group A2), suppressed adenine nucleotide degradation during ischemia and enhanced the resynthe-sis of high-energy phosphates after reperfusion. Although structural abnormalities in postreperfusion liver tissues were markedly ameliorated in all treated groups, Group A2 showed significantly less neutrophil infiltration. Liver injury from warm ischemia and reperfusion was attenuated with all lazaroid compounds, of which U-74500A at 5 mg/kg exhibited the most significant protective activity.