Abstract: ObjectiveTo investigate the mechanism and the protective effect of heat shock protein 27 (HSP₂₇) on rat cardiomyocytes when ischemic preconditioning performed.MethodsCultured rat cardiomyocytes were divided into four groups: control group, ischemic group,ischemic preconditioning group and cyclohexamide group. Cell viabilities were analyzed by MTT. The apoptosis was evaluated with DNA ladder and flow cytometry Annexin V Flous staining. Western Blot was used to determine the expression of HSP₂₇ and caspase-3 in cardiomyocytes.ResultsIschemic preconditioning could improve cell viability. The apoptosis ratio in ischemic preconditioning group was significantly less than that in ischemic group. These were accompanied by an increase in the expression of HSP₂₇ and a decrease in caspase-3. The expression of the increased HSP₂₇ and the protective effect induced by ischemic preconditioning were completely abolished by the presence of cycloheximide, a translation inhibitor.ConclusionThe expression of HSP₂₇ induced by ischemic preconditioning plays an important role in protecting cardiomyocytes, and the mechanism is possibly related to the inhibition of cell apoptosis.

Key words: heat shock protein 27 (HSP₂₇), ischemic preconditioning, cardiomyocyte, apoptosis, caspase-3