title: Grape seed proanthocyanidins protect cardiomyocytes from ischemia and reperfusion injury via Akt-NOS signaling.
abstract: 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 microg/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 Nomega-nitro-L-arginine methyl ester (L-NAME, 200 microM) 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 microM) abrogated GSPE-induced protection [44.3% +/- 2.2% (GSPE + API-2) vs. 27.0% +/- 4.3% (GSPE alone), P < 0.01], attenuated the enhanced phosphorylation of Akt at Ser473 in GSPE-treated cells and attenuated GSPE-induced NO increases. Simultaneously blocking NOS activation (L-NAME) and Akt (API-2) resulted in decreased NO levels similar to using each inhibitor independently. These data suggest that in the context of GSPE stimulation, Akt may help activate eNOS, leading to protective levels of NO. GSPE offers an alternative approach to therapeutic cardioprotection against I/R injury and may offer unique opportunities to improve cardiovascular health by enhancing NO production and increasing Akt-eNOS signaling.
authors.affiliation: Department of Medicine, Emergency Resuscitation Center, University of Chicago, Illinois 60637, USA.
authors.forename: Zuo-Hui
authors.initials: ZH
authors.lastname: Shao
authors.forename: Kimberly R
authors.initials: KR
authors.lastname: Wojcik
authors.forename: Anar
authors.initials: A
authors.lastname: Dossumbekova
authors.forename: Chinwang
authors.initials: C
authors.lastname: Hsu
authors.forename: Sangeeta R
authors.initials: SR
authors.lastname: Mehendale
authors.forename: Chang-Qing
authors.initials: CQ
authors.lastname: Li
authors.forename: Yimin
authors.initials: Y
authors.lastname: Qin
authors.forename: Willard W
authors.initials: WW
authors.lastname: Sharp
authors.forename: Wei-Tien
authors.initials: WT
authors.lastname: Chang
authors.forename: Kimm J
authors.initials: KJ
authors.lastname: Hamann
authors.forename: Chun-Su
authors.initials: CS
authors.lastname: Yuan
authors.forename: Terry L Vanden
authors.initials: TL
authors.lastname: Hoek
mesh_terms: D000818:Animals; D002642:Chick Embryo; D056604:Grape Seed Extract; D015428:Myocardial Reperfusion Injury / Q000517:prevention & control*; D032383:Myocytes, Cardiac / Q000187:drug effects*; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D010936:Plant Extracts / Q000494:pharmacology*; D044945:Proanthocyanidins / Q000494:pharmacology*; D020011:Protective Agents; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D012639:Seeds; D015398:Signal Transduction / Q000187:drug effects*; D027843:Vitis
chemical_list: D056604:Grape Seed Extract; C511402:Grape Seed Proanthocyanidins; D010936:Plant Extracts; D044945:Proanthocyanidins; D020011:Protective Agents; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052250:Nitric Oxide Synthase Type III; D051057:Proto-Oncogene Proteins c-akt