Influence of ethanol extract of Ginkgo biloba leaves on the isolated rat heart work and mitochondria functions

Abstract

In this study we attempted to elucidate whether the effects of ethanol extract of Ginkgo biloba leaves (GBE) observed previously on isolated rat heart mitochondria may be realized in situ (in case of isolated heart perfused under normal conditions and under ischemia-reperfusion). We found that GBE at low concentrations (0.01, 0.05 and 0.1 [mu]l/ml) does not affect heart rate and parameters of electrocardiogram (ECG), but produces a small increase in coronary flow. Higher concentration of GBE (0.2 and 0.3 [mu]l/ml) diminished heart rate, coronary flow and tended to enhance the parameters of ECG. The contractility of isolated rat heart as well as mitochondrial NADH fluorescence decreased in a GBE concentration-dependent manner. Mitochondria isolated from hearts pre-perfused with GBE (0.05 [mu]l/ml) for 20 min prior to non-flow global ischemia-reperfusion (45 min/15 min) showed higher respiratory rates with pyruvate + malate in State 2 and State 3, higher respiratory control index and diminished H2O2 generation as compared to untreated group. Higher GBE concentration, 0.4 [mu]l/ml, had no effect on H2O2 generation and did not prevent the ischemia-reperfusion induced decrease of pyruvate + malate oxidation in State 3 but even enhanced it. However, in the case of non-ischemic perfusions, this GBE concentration had no significant effect on these parameters of respiratory functions of isolated heart mitochondria.