Ginsenoside Rb1 protects cardiomyocytes against CoCl2-induced apoptosis in neonatal rats by inhibiting mitochondria permeability transition pore opening

Abstract

Aim: To investigate whether mitochondria permeability transition pore (mPTP) opening was involved in ginsenoside Rb1 (Gs-Rb1) induced anti-hypoxia effects in neonatal rat cardiomyocytes ex vivo. Methods: Cardiomyocytes were randomly divided into 7 groups: control group, hypoxia group (500 μmol/L CoCl2), Gs-Rb1 200 μmol/L group (CoCl2 intervention+Gs-Rb1), wortmannin (PI3K inhibitor) 0.5 μmol/L group, wortmannin+Gs-Rb1 group, adenine 9-β-D-arabinofuranoside (Ara A, AMPK inhibitor) 500 μmol/L group, and Ara A and Gs-Rb1 group. Apoptosis rate was determined by using flow cytometry. The opening of the transient mPTP was assessed by using co-loading with calcein AM and CoCl2 in high conductance mode. Expression of GSK-3β, cytochrome c, caspase-3 and poly (ADP-ribose) polymerase (PARP) was measured by using Western blotting. ΔGSK-3β was defined as the ratio of p-Ser9-GSK-3β to total GSK-3β. Results: CoCl2 significantly stimulated mPTP opening and up-regulated the level of ΔGSK-3β. There was a statistically significant positive correlation between apoptosis rate and mPTP opening, between apoptosis rate and ΔGSK-3β, and between mPTP opening and ΔGSK-3β. Gs-Rb1 significantly inhibited mPTP opening induced by hypoxia (41.3%±2.0%, P<0.001). Gs-Rb1 caused a 77.3%±3.2% reduction in the expression of GSK-3β protein (P<0.001) and a significant increase of 1.182±0.007-fold (P=0.0001) in p-Ser9-GSK-3β compared with control group. Wortmannin and Ara A significantly inhibited the effect of Gs-Rb1 on mPTP opening and ΔGSK-3β. Gs-Rb1 significantly decreased expression of cytochrome c (66.1%±1.7%, P=0.001), caspase-3 (56.5%±2.7%, P=0.001) and cleaved poly ADP-ribose polymerase (PARP) (57.9%±1.4%, P=0.001). Conclusion: Gs-Rb1 exerted anti-hypoxia effect on neonatal rat cardiomyocytes by inhibiting GSK-3β-mediated mPTP opening. © 2010 CPS and SIMM. All rights reserved.