Panax quinquefolium saponins protect rat myocardium from ischemia/reperfusion injury through attenuating excessive endoplasmic reticulum stress

AIM: To investigate whether excessive endoplasmic reticulum stress (ERS) is involved in the protective mechanism of Panax quinquefolium saponins (PQS) against ischemia/reperfusion (I/R) injury in rat myocardium. METHODS: The model of myocardial I/R injury in vivo was made by ligating the left anterior descending artery for 45 min followed by 24 h of reperfusion in SD rats. The hemodynamics and serum content of cardiac troponin T (cTnT) were measured. The myocardial infarct size was measured by Evans blue and 2, 3, 5-triphenyltetrazolium chloride (TTC) staining. Cardiomyocyte apoptosis was detected using in situ TDT-mediated dUTP nick end labeling (TUNEL). The protein levels of glucose-regulated protein 78 (GRP78), calreticulin (CRT), C/EBP homologous protein (CHOP), caspase-12, apoptosis-associated proteins Bax and Bcl-2 were determined by Western blotting. RESULTS: Compared with I/R group, the mean arterial pressure in PQR+IR group was decreased by 32.0%, and left ventricular±dp/dtmax was increased by 64.0% and 35.0%， respectively.The serum content of cTnT was decreased by 53.3%, the percentage of area of necrosis (AN)/area at risk (AAR) was reduced by 65.5% and the apoptosis rate was decreased by 54.9%.The myocardial pathological changes were improved. Bcl-2 protein expression was increased by 110.0% and that of Bax was decreased by 47.8%. CRT protein expression was decreased by 43.4 %, CHOP protein expression and the protein level of cleaved caspase-12 were decreased by 38.6% and 23.7% in PQS+I/R group. CONCLUSION: PQS alleviates I/R injury in myocardium by inhibition of excessive ERS.