Effect of hypoxic postconditioning and diazoxide postconditioning on calreticulin expression during hypoxia/reoxygenation in rat cardiomyocytes / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effect of hypoxic postconditioning and diazoxide postconditioning on the calreticulin expression during hypoxia/reoxygenation (H/R) in rat cardiomyocytes. Methods Primary cultured male SD rat cardiomyocytes were randomly divided into 6 groups (n = 8 each): control group (group C),H/R group; hypoxic postconditioning group (group HP) and diazoxide postconditioning group (group DP). Group C were cultured continuously for 2 h. Group H/R, Hp and DP were exposed to 45 min hypoxia (95% N2-5% CO2)followed by 1 h reoxygenation. In group HP, the cells were subjected to three cycles of 3 min hypoxia at 3 min intervals at the end of 45 min hypoxia before 1 h reoxygenation. In group DP, diazoxide 50 μmol/L was giyen at the end of hypoxia. Caspase-3 activity, calreticulin expression and intracellular free calcium ion concentrations were determined. Results Compared with group C, caspase-3 activity was significantly increased in the other groups,the calreticulin expression was up-regulated in group HP and DP, and the free calcium ion concentrations were increased in group H/R (P ＜ 0.05 or 0.01). Compared with group H/R, caspase-3 activity was significantly decreased in HP and DP, the calreticulin expression was up-regulated and the free calcium ion concentrations were decreased in group HP and DP (P ＜ 0.01). Conclusion Hypoxic postconditioning and diazoxide postconditioning attenuate H/R injury in rat cardiomyocytes through up-regulating the expression of calreticulin and reducing intracellular calcium overload.