Protective effects of EGCg or GCg, a green tea catechin epimer, against postischemic myocardial dysfunction in guinea-pig hearts
- 作者：Masaya Hirai ; Yoshihiro Hotta ; Naohisa Ishikawa ; Yasushi Wakida ; Yoshitaka Fukuzawa ; Fumitaka Isobe ; Akinobu Nakano ; Taku Chiba ; Norihisa Kawamura
- 关键词：Langendorff hearts ; Green tea catechin ; Electron paramagnetic resonance (EPR) ; Mitochondrial permeability transition pore (MPTP) ; Caspase 3
- 刊名：Life Sciences
- 出版年：2007
- 期刊代码：62_00243205
- 类别：imm
- 出版时间：20 February 2007
- 卷：80
- 期：11
- 页码：1020-1032
- 文件大小：618 K
摘要
The protective effects of (−)-epigallocatechin-3-gallate (EGCg) or the C-2 epimer, (−)-gallocatechin-3-gallate (GCg), afforded by their antioxidative activity among green tea catechins were investigated in perfused guinea-pig Langendorff hearts subjected to ischemia and reperfusion. The recovery (%) of the left ventricular developed pressure from ischemia by reperfusion was 34.4%in the control, while in the presence of EGCg (3 × 10− 5 M) or GCg (3 × 10− 6 M, a more diluted concentration than that of EGCg), it led to a maximal increase of 78.4%or 76.2%, consistent with a significant preservative effect on the tissue level of ATP at the end of ischemia or reperfusion. In the perfused preparation of mitochondria, EGCg (10− 5 M) inhibited mitochondrial Ca2+ elevation by changes in the Ca2+ content or the acidification of perfusate, similarly to findings with cyclosporin A, a well known inhibitor of the mitochondrial permeability transition pore. By in vitro electron paramagnetic resonance (EPR), EGCg or GCg was found to directly quench the activity of active oxygen radicals, with the strongest activity in tea catechins. EGCg or GCg decreased the caspase-3 activity induced apoptosis. Therefore, it is concluded that the beneficial effects of EGCg or GCg play an important role in ischemia–reperfusion hearts in close relation with nitric oxide (NO), active oxygen radicals and biological redox systems in mitochondria.