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 micromol/L CoCl(2)), Gs-Rb1 200 micromol/L group (CoCl(2) intervention+Gs-Rb1), wortmannin (PI3K inhibitor) 0.5 micromol/L group, wortmannin+Gs-Rb1 group, adenine 9-beta-D-arabinofuranoside (Ara A, AMPK inhibitor) 500 micromol/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 CoCl(2) in high conductance mode. Expression of GSK-3beta, cytochrome c, caspase-3 and poly (ADP-ribose) polymerase (PARP) was measured by using Western blotting. DeltaGSK-3beta was defined as the ratio of p-Ser9-GSK-3beta to total GSK-3beta.
Results: CoCl(2) significantly stimulated mPTP opening and up-regulated the level of DeltaGSK-3beta. There was a statistically significant positive correlation between apoptosis rate and mPTP opening, between apoptosis rate and DeltaGSK-3beta, and between mPTP opening and DeltaGSK-3beta. 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-3beta protein (P<0.001) and a significant increase of 1.182+/-0.007-fold (P=0.0001) in p-Ser9-GSK-3beta compared with control group. Wortmannin and Ara A significantly inhibited the effect of Gs-Rb1 on mPTP opening and DeltaGSK-3beta. 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-3beta-mediated mPTP opening.