Grape seed proanthocyanidin extract attenuates oxidant injury in cardiomyocytes

This study sought to test whether grape seed proanthocyanidin extract (GSPE) attenuates exogenous and endogenous oxidant stress induced in chick cardiomyocytes and whether this cytoprotection is mediated by PKC activation, mito K-ATP channel opening, NO production, oxidant scavenging. or iron chelating effects. Cells were exposed to hydrogen peroxide (H2O2) (exogenous oxidant stress, 0.5 mM) or antimycin A (endogenous oxidant stress, 100 muM) for 2 h following pretreatment with GSPE at various concentrations for 2 h. Cells were also pretreated with GSPE or with inhibitors of PKC (chelerytherine), mito K-ATP channel (5-hydroxydecanoate), nitric oxide synthase (nitro-L-arginine methyl ester) for 2 h. Oxidant stress was measured by 2',7'-dichlorofluorescin diacetate and cell viability was assessed using propidium iodide. Free radical scavenging and iron chelating ability was tested in vitro. GSPE dose-dependently attenuated oxidant formation and significantly improved cell survival and contractile function. However, inhibitors of PKC, mito K-ATP channel or NO synthase failed to abolish the protective action of GSPE during H2O2 or antimycin A exposure. In vitro studies suggested that GSPE scavenges H2O2, hydroxyl radical and superoxide, and may chelate iron. These results indicate that GSPE confers cardioprotection against exogenous H2O2- or antimycin A-induced oxidant injury. Its effect does not require PKC, mito K-ATP channel, or NO synthase, presumably because it acts by reactive oxygen species scavenging and iron chelating directly. (C) 2003 Elsevier Science Ltd. All rights reserved.