OBJECTIVETo investigate the significance of PKC and p44/42 mitogen-activated protein kinase (MAPK) signal transduction in ischemic preconditioning (IP).

METHODSThrough 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.

RESULTSSimilar 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.

CONCLUSIONThese results suggest that p44/42 MAPK pathway plays a vital role in the protection of hepatocytes in ischemic preconditioning.