OBJECTIVETo determine whether the cardioprotection of puerarin (Pue) against hypoxia/reoxygenation injury is mediated by mitochondrial ATP-sensitive potassium channel (mitoK(ATP)) and/or mitochondria calcium-activated potassium channel(mitoK(Ca)).

METHODSCardiomyocytes were isolated from male Sprague-Dawley rats and hypoxia/reoxygenation injury was induced by myocyte pelleting model. Cell viability was assessed by trypan blue exclusion and mitochondrial membrane potential was measured by loading with TMRE. 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 hypoxia/reoxygenation injury, while mitochondrial ATP-sensitive potassium channel inhibitor 5-hydroxydecanoate (5-HD, 100 micromol/L, 20 min) or mitochondrial calcium-activated potassium channel blocker paxilline (Pax, 1 micromol/L, 5 min) attenuated the effect of puerarin. The pretreatment with Pue at 0.24 mmol/L for 5 min attenuated collapse of delta-psim induced by hypoxia/reoxygenation injury, 5-HD and Pax abrogated the effect of Pue. In mitochondria isolated from hearts pretreated with Pue, a significant inhibition of Ca(2+)-induced swelling was observed, and this inhibition was attenuated by 5-HD and Pax.

CONCLUSIONThese findings indicate that Pue protects cardiomyocytes against hypoxia/reoxygenation injury via activating mitoK(ATP) channel and mitoK(Ca) channel, and inhibiting mitochondrial permeability transition pore opening.