Improvement of Ventricular Mechanical Properties by Puerarin Involves Mitochondrial Permeability Transition in Isolated Rat Heart during Ischemia and Reperfusion

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. In isolated rat hearts subjected to 30 min regional ischemia and 120 min reperfusion, pretreatment with Pue at 0.24 mmol/L for 5 min before ischemia increased myocardial formazan content, an index of myocardial viability, reduced lactate dehydrogenase release, improved recovery of the maximal rise/fall rate of left ventricular pressure, 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. These findings indicate that Pue protects the myocardium against ischemia and reperfusion injury via inhibiting mitochondrial permeability transition pore opening and activating the mitochondrial ATP-sensitive potassium channel.