AIMTo determine whether the cardioprotection of puerarin (Pue) against H202-stress is mediated by mitochondrial transmembrane pores and/or channels.

METHODSCardiomyocytes were isolated from male Sprague-Dawley rats. Cell viability was assessed by trypan blue exclusion and mitochondrial membrane potential was measured by loading with Rhodamine 123. The opening of mitochondrial permeability transition pore was determined spectrophotometrically.

RESULTSPretreatment with Pue at 0.24 mmol/ L for 5 min increased the cell viability against H2O2-stress, while mitochondrial calcium-activated potassium channel blocker paxilline (Pax, 1 micromol/L, 5 min) or PKC inhibitor(chelerythrine, 5 micromol/L, 30 min) attenuated the effect of puerarin. The pretreatment with Pue at 0.24 mmol/L for 5 min or mitochondrial calcium-activated potassium channel opener NS 1619 (10 micromol/L, 10 min) attenuated mitochondrial depolarization induced by H2O2-stress, while mitochondrial permeability transition pore opener atractyloside (20 micromol/L, 20 min) abrogated the effect of Pue. In mitochondrial isolated from hearts pretreated with 0.24 mmol/L Pue for 5 min, a significant inhibition of Ca2+ -induced swelling was observed, which inhibition was attenuated by Pax (1 micromol/L, 5 min).

CONCLUSIONThese findings indicate that Pue protects cardiomyocytes against H2O2-stress via inhibiting mitochondrial permeability transition pore opening and activating mitochondrial calcium-activated potassium channel.