The aim of the present study was to determine whether the clinically effective cardioprotection conferred by
puerarin (Pue) against
ischemia and reperfusion is mediated by mitochondrial transmembrane pores and/or channels. Hearts isolated from male Sprague-Dawley rats were perfused on a Langendorff apparatus and subjected to 30 min of global
ischemia followed by 120 min of reperfusion. The production of
formazan, which provides an index of myocardial viability, was measured by absorbance at 550 nm, and the level of
lactate dehydrogenase (LDH) in the coronary effluent was determined. In this model, Pue (0.0024-2.4 mmol/l) had a dose-dependent, negatively inotropic effect. Pretreatment with Pue at 0.24 mmol/l for 5 min before
ischemia increased myocardial
formazan content, reduced LDH release, improved recovery of left ventricular end-diastolic pressure and rate-pressure product (left ventricular developed pressure multiplied by heart rate) during reperfusion. Administration of
atractyloside (20 micromol/l), an opener of the
mitochondrial permeability transition pore, for the first 20 min of reperfusion, and
5-hydroxydecanoate (100 micromol/l), the mitochondrial-specific
ATP-sensitive potassium channel blocker, for 20 min before
ischemia, attenuated the protective effects of Pue. In mitochondria isolated from hearts pretreated with 0.24 mmol/l Pue for 5 min, a significant inhibition of Ca(2+)-induced swelling was observed, and this inhibition was attenuated by
5-hydroxydecanoate. In isolated ventricular myocytes, pretreatment with Pue prevented
ischemia-induced cell death and depolarization of the mitochondrial membrane, and
atractyloside and
5-hydroxydecanoate attenuated the effects of Pue. These findings indicate that
puerarin protects the myocardium against
ischemia and
reperfusion injury via inhibiting
mitochondrial permeability transition pore opening and activating the mitochondrial
ATP-sensitive potassium channel.