Sabiporide Reduces Ischemia-Induced Arrhythmias and Myocardial Infarction and Attenuates ERK Phosphorylation and iNOS Induction in Rats

Henri Doods,Dongmei Wu

doi:10.1155/2013/504320

Abstract

The aim of the present study was to investigate the effects of sabiporide, a potent and selective NHE1 inhibitor, on myocardial ischemia-induced arrhythmias and myocardial infarction and the possible pathways related to the cardioprotection afforded by sabiporide treatment. Anesthetized rats were subjected to myocardial ischemia via left main coronary artery occlusion for 30 minutes, followed by 2 hours of reperfusion. Administration of sabiporide (0.01–3.0 mg/kg) prior to coronary artery occlusion dose-dependently reduced ischemia-induced arrhythmias and infarct size with an ED50 value of 0.14 mg/kg. Administration of sabiporide (1.0 mg/kg) prior to reperfusion also reduced infarct size by 38.6%. The reduction in infarct size was accompanied by a decrease in circulating levels of creatine phosphokinase and troponin I. In addition, sabiporide (1.0 mg/kg) given prior to coronary artery occlusion or immediately before reperfusion significantly reduced phosphorylation of the extracellular signal-regulated kinase (ERK1/2) and the expression of the inducible nitric oxide synthase (iNOS) following myocardial ischemia-reperfusion. This study demonstrates that sabiporide is a potent and effective cardioprotective agent during myocardial ischemia and reperfusion, by reducing serious ventricular arrhythmias and myocardial infarct size. The cardioprotection afforded by sabiporide is attributed in part to inhibition of ERK1/2 phosphorylation and suppression of iNOS expression.

Highlights

Na+/H+ exchangers (NHEs) are membrane proteins that regulate ion uxes
5 of 17 control rats died by VF-induced cardiac arrest during the 30minute coronary artery occlusion period
Administration of sabiporide prior to coronary artery occlusion dosedependently reduced the number of Ventricular premature beats (VPBs), the duration of Ventricular tachycardia (VT), and the incidence of VF (Figures 1(a), 1(b), and 1(c))

Summary

Introduction

Na+/H+ exchangers (NHEs) are membrane proteins that regulate ion uxes. Physiologically, they extrude one intracellular proton in exchange for one extracellular sodium, thereby regulating intracellular pH. NHE1, the housekeeping isoform present in all mammalian cells, is the most predominant isoform in cardiomyocytes [1, 2] It is implicated in heart hypertrophy and heart failure and mediates myocardial damage that occurs a er ischemia-reperfusion injury. For this reason, regulation of NHE1 has been proposed as a therapeutic target for cardioprotection [1,2,3]. The efficacy of sabiporide has not been examined in an animal model of regional ischemia-reperfusion injury. e present study investigated the dose-response effects of sabiporide on myocardial ischemia-induced arrhythmias and myocardial infarction in anesthetized rats and examined the potential signaling pathways underlying this protective response

Methods

Results

Discussion