[Protecting effects of p44/42 MAPK signal transduction pathway on hepatocytes in ischemic preconditioning].

ABSTRACT

OBJECTIVE: To investigate the significance of PKC and p44/42 mitogen-activated protein kinase (MAPK) signal transduction in ischemic preconditioning (IP). METHODS: Through liver cell IP models, PKC inhibitor and MEK inhibitor were utilized to analyze the phosphorylation level of p44/42 MAPK and cell viability was also observed. Rat liver IP models were established which were treated with various drugs. Then the phosphorylation level of p44/42 MAPK in vivo and serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) concentrations were detected. And cellular structures were observed under light microscopy. RESULTS: Similar results were obtained in vivo and in vitro IP models. Compared with the ischemia reperfusion (IR) group in vivo, the phosphorylation level of p44/42 MAPK was obviously increased in IP treated rats (q = 27.217, P < 0.01), and the cellular structure injured slightly. The concentrations of serum ALT and AST in IP group were significantly lower than those in IR group (281.0 U/L +/-35.6 U/L vs 762.8 U/L +/-130.5 U/L and 407.7 U/L +/-73.7 U/L vs 820.9 U/L +/-111.3 U/L, P < 0.01). However, opposite changes were found in PKC and MEK inhibited groups, when compared to IP group. The phosphorylation level of p44/42 MAPK was obviously decreased, the liver tissues injured evidently, and the concentrations of serum ALT and AST (645.61 U/L +/-90.4 U/L, 678.6 U/L +/-136.5U/L and 466.2 U/L +/-82.8 U/L, 732.9 U/L +/-91.1 U/L, respectively) were significantly greater than those in IP group. CONCLUSION: These results suggest that p44/42 MAPK pathway plays a vital role in the protection of hepatocytes in ischemic preconditioning.