Abstract 3889: Persistent Cardioprotection by Regular Ethanol Consumption After Abstention Depends on eNOS but not iNOS Activity After Reperfusion

Abstract

We previously found regular ethanol consumption induces cardioprotection against ischemia-reperfusion (I-R) injury with persistent protection after abstention. The mechanism of this continued protection remains unclear. We now determine how long ethanol cardioprotection persists after abstention and whether inducible and/or endothelial nitric oxide synthase (iNOS and eNOS) play a role in this continued cardioprotection. Isolated perfused hearts from control (CTL) and ethanol-treated (ETOH) guinea pigs were subjected to 30 min global ischemia and 120 min reperfusion. ETOH received 5% ethanol in their drinking water for 8 weeks. I-R was performed on ETOH hearts at 0, 4, 7 and 14 days after abstention. To determine whether iNOS and eNOS play a role in this persistent cardioprotection, a NOS inhibitor, L-NAME (100μM) was given before ischemia or during reperfusion. Contractile recovery was monitored by left ventricular developed (LVDP) and end-diastolic (LVEDP) pressures. Infarct size (IS) was determined by triphenyltetrazolium chloride staining. Myocardial iNOS and eNOS were determined by Western blot and immunohistochemically. After I-R, ETOH at 0, 4 and 7, but not 14 days abstention, had significantly higher LVDP (62±5, 64±5, 54±4, 34±3 vs . 26±3 mmHg, respectively), and lower LVEDP (17±6, 21±3, 30±6, 43±1 vs. 59±5 mmHg, respectively) compared to CTL. IS was significantly reduced in ETOH at 0, 4 and 7, but not 14 days abstention, compared to CTL (24±3, 24±2, 30±3, 37±2 vs. 47±3%, respectively). L-NAME given during reperfusion, but not before ischemia, abolished cardioprotection at 0 and 7 days abstention ( IS: 42±3, 45±3%, N.S. vs. CTL, respectively). Western blot analysis demonstrated upregulation of eNOS expression up to 7 days, but not 14 days abstention. Expression of iNOS was reduced at 0 day. eNOS immunoreactivity was greater at 0, 4 and 7 days and iNOS at 14 days, compared to CTL. Chronic cardioprotection against I-R by regular ethanol consumption persists for at least 7 days after abstention. Increased eNOS activity after reperfusion plays a role in this persistent cardioprotection.