Anti-hypoxic effect of ginsenoside Rbl on neonatal rat cardiomyocytes is mediated through the specific activation of glucose transporter-4 ex vivo

Abstract

Aim:The aim of this study was to investigate whether Gs-Rbl relieves the CoCl 2 -induced apoptosis of hypoxic neonatal rat cardiomyocytes and in which the role of glucose transporter-4 (GLUT-4). Methods: 10, 50, 100, 200, 400, and 500 µmol/L), adenine 9-β-D-arabinofuranoside (ara A, 500 µmol/L; AMPK inhibitor) and wortmannin (0.5 µmol/L; PI3K inhibitor) only in combination with 200 µmol/L Gs-Rbl were administered in hypoxic cardiomyocytes, which were induced by 500 µmol/L CoCl 2 for 12 h. Then, the apoptotic rate (AR), 2-[ 3 H]-deoxy-D-glucose (2-[ 3 H]-DG) uptake, and the expression of GLUT-4 (including in plasma membrane, PM), phospho-AMPKα (Thr172), AMPKα and Akt in cells were assayed. Results: Compared with simple hypoxia (0 µmol/L Gs-Rbl), Gs-Rb1 greater than 10 µmol/L significantly decreased the apoptotic rate (P<0.01) and significantly increased 2-[ 3 H]-DG uptake (P<0.01), GLUT-4 content in cells and PM (P<0.01), AMPK activity (P<0.01) and Akt (P<0.01) levels in a dose-dependent manner. AMPK activity was completely suppressed by ara-A, just as Akt was suppressed by wortmannin. The AR, glucose uptake and GLUT-4 levels in cells and PM were partly down-regulated by ara-A or wortmannin. Conclusion: Gs-Rb1 may protect neonatal rat cardiomyocytes from apoptosis induced by CoCl 2 . The anti-apoptotic effect of Gs-Rb1 may occur by improving glucose uptake, in which GLUT-4 translocation and expression played a key role. Both the AMPK and the PI3K/Akt pathways may take part in the anti-hypoxic efficacy of Gs-Rb1.

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

“…Our previous study demonstrated that Gs-Rb1, by improving glucose uptake, plays an important role in protecting neonatal rat cardiomyocytes from CoCl 2 -induced apoptosis ex vivo [5] . This role may be controlled by the translocation of GLUT-4 mediated by both AMPK and/or PI3K signaling cascade.…”

“…As in our previous study [5] , cardiomyocyte cultures were prepared from hearts of 1-3-d-old rats. In brief, ventricles had been separated and cut into 1 mm 3 pieces and digested (37 ºC, 10 min, two to three such cycles to achieve full digestion) with phosphate-buffered saline (PBS) containing 0.08% trypsin and 0.05% collagenase II (Gibco).…”

“…CoCl 2 -induced chemical hypoxia and Gs-Rb1 intervention According to our previous experimental results [5] , 500 µmol/L CoCl 2 , 200 µmol/L Gs-Rb1, 500 µmol/L adenine 9-β-Darabinofuranoside (Ara A, AMPK inhibitor) and 0.5 µmol/L wortmannin (PI3K inhibitor) were freshly prepared. Cells were randomly divided into seven groups as follows: control group (normal oxygen group), hypoxia group (500 µmol/L CoCl 2 intervention), Gs-Rb1 group (200 µmol/L Gs-Rb1 and 500 µmol/L CoCl 2 intervention), W-1 group (0.5 µmol/L wortmannin and 500 µmol/L CoCl 2 intervention), W-2 group (0.5 µmol/L wortmannin intervention basing on 200 µmol/L Gs-Rb1 and 500 µmol/L CoCl 2 intervention), A-1 group (500 µmol/L Ara A and 500 µmol/L CoCl 2 intervention) and A-2 group (500 µmol/L Ara A intervention basing on 200 µmol/L Gs-Rb1 and 500 µmol/L CoCl 2 intervention).…”

“…Ginsenoside-Rbl (Gs-Rbl), a main component of Ginsenosides extracted from Ginseng (the root of Panax ginseng CA Meyer, family Araliaceae, a traditional medicine in Asian countries), has been reported to inhibit ischemic/reperfusion injury as a result of myocardial infarction in vivo [1][2][3][4] . Gs-Rbl may also protect neonatal rat cardiomyocytes from CoCl 2 -induced apoptosis depending on whether the PI3K or AMPK signaling cascade results in GLUT4 translocation ex vivo [5] . The mitochondrial permeability transition pore (mPTP) is a mega-channel with permeability to all molecules of less than 1.5 kDa.…”

“…Thus, we investigated whether Gs-Rb1 influenced the expression of GSK-3β and whether a correlation existed between GSK-3β and mPTP opening. In addition, considering that the anti-hypoxia ability of Gs-Rb1 is mediated by both phosphoinositide 3-kinase (PI3K) and AMP-activated protein kinase (AMPK) signaling [5] , we further evaluated whether the mechanisms contributing to adjust both mPTP opening and the activity of GSK-3β were mediated by both PI3K and AMPK signaling ex vivo.…”