Chronergy of hypoxia on endoplasmic reticulum stress in neonate rat myocardial cells / 解放军医学杂志

ABSTRACT

Objective To investigate the expression of endoplasmic reticulum stress protein induced by hypoxia in different hypoxic phase, and study the significance of endoplasmic reticulum stress on the apoptosis of rats' myocardial cells in vitro. Methods The cultured myocardial cells of neonate rats were divided randomly into 0-hour group (control group) and hypoxia for 6-hour, 12-hour, 18-hour, 24-hour and 30-hour groups. Animals in hypoxia groups were treated with mixed gas of 95% N2 and 5% CO2 for different periods, and those in control group were without hypoxic treatment. Expressions of GRP78, CHOP and Caspase-12 protein were examined by Western blotting, and the apoptosis of myocardial cells was detected by flow cytometry. Results Basic expression of GRP78 was observed in control group. Up-regulation of GRP78 expression was induced by hypoxia for 6 hours. Significant increase of GRP78 expression appeared at 12-hour, and peaked at 18-hour, after hypoxia (P<0.05). Decrease of GRP78 expression was observed at 24-hour and 30-hour after hypoxia. Up-regulation of CHOP and Caspase-12 expression was detected at 12-hour after hypoxia exposure and maintained during 30-hour hypoxia exposure. Typical manifestation of myocardial cells apoptosis appeared at 12-hour after hypoxia. Compared with the control group, the apoptosis rate increased significantly at 18-hour, 24-hour and 30-hour after exposure to hypoxia (P<0.01). Conclusion Endoplasmic reticulum stress in myocardial cells play different roles in different hypoxic phase.