Grape Seed Proanthocyanidins Protect Cardiomyocytes from Ischemia and Reperfusion Injury Via Akt-Nos Signaling

Ischemia/reperfusion (I/R) injury in cardiomyocytes is related to excess reactive oxygen species (ROS) generation and can be modulated by nitric oxide (NO). We have previously shown that grape seed proanthocyanidin extract ( GSPE), a naturally occurring antioxidant, decreased ROS and may potentially stimulate NO production. In this study, we investigated whether GSPE administration at reperfusion was associated with cardioprotection and enhanced NO production in a cardiomyocyte I/R model. GSPE attenuated I/R-induced cell death [18.0 +/- 1.8% (GSPE, 50 mu g/ml) vs. 42.3 +/- 3. 0% (I/R control), P<0.001], restored contractility (6/6 vs . 0/6, respectively), and increased NO release. The NO synthase (NOS) inhibitor N omega-nitro-L-arginine methyl ester (L-NAME, 200 mu M) significantly reduced GSPE-induced NO release and its associated cardioprotection [32.7 +/- 2.7 % (GSPE + L-NAME) vs. 18.0 +/- 1.8% (GSPE alone), P<0.01]. To determine whether GSPE induced NO production was mediated by the Akt-eNOS pathway, we utilized the Akt inhibitor API- 2. API-2 (10 mu M) abrogated GSPE-induced protection [44.3% +/- 2.2% (GSPE + API-2) vs. 27.0% +/- 4.3% (GSPE alone), P