Lack of cardioprotection from metabolic support with glutamine or glutamate in a porcine coronary occlusion model

Abstract

Objective. Previous experimental studies indicate that glutamine or glutamate may provide cardioprotection by improving the oxidative metabolism in myocardial ischemia. We investigated the effect of glutamine or glutamate, given during reperfusion, on resulting infarct size and hemodynamic recovery. Design. A porcine coronary occlusion model was applied. Infusions were initiated 15 min before reperfusion and supplemented with intracoronary bolus doses at reperfusion. The primary outcome measure was infarct size in relation to area at risk determined by a standard tissue staining procedure. Secondary outcome measures were the hemodynamic variables. Results. The infarct sizes as a proportion of the area at risk (mean±SD) were: control group, 0.64±0.19 (n = 9); glutamine group, 0.87±0.07 (p <0.05 vs control group) (n = 8); glutamate group, 0.72±0.11 (n = 9). Glutamine increased systemic vascular resistance, while glutamate preserved cardiac output during infusion. Conclusion. Substrate supplementation with the anaplerotic precursors glutamine and glutamate is ineffective as adjunctive therapy for severe myocardial ischemia. Beneficial effects documented in less complex experimental systems could not be transferred to a more pathophysiological relevant model. © 2005 Taylor & Francis Group Ltd.