RESUMO
UNLABELLED: Chronic ingestion of small doses of ethanol protects the myocardium from ischemic damage. It was demonstrated that short-term administration of ethanol (SAE) enhances the recovery of stunned myocardium in acutely instrumented, anesthetized dogs. It is unclear whether this beneficial effect of SAE also occurs in awake dogs. Therefore, we investigated the effects of SAE on regional myocardial stunning in awake dogs. Thirty-six dogs were chronically instrumented for measurement of heart rate, left atrial, aortic, and left ventricular pressure, left systolic ventricular contactility (dP/dt(max)) and diastolic ventricular function (dP/dt(min)), and regional myocardial wall-thickening fraction (WTF). Occluders around the left anterior descending (LAD) artery allowed the induction of reversible ischemia in the LAD-perfused myocardium. The dogs were assigned to one of three groups that differed in the dose of ethanol administered in the ethanol experiment (I, 0.125 g/kg [n = 12]; II, 0.25 g/kg [n = 12]; III, 0.5 g/kg [n = 12]). In each group, the dogs underwent two ischemic episodes (randomized crossover fashion; separate days): 10 min of LAD occlusion after the application of ethanol IV over 30 min (ethanol group) and without ethanol (control). WTF and hemodynamic variables were measured at baseline and at predetermined time points until complete recovery of myocardial stunning occurred. LAD-ischemia led to a significant decrease of LAD-WTF in all groups. There was no difference in WTF and hemodynamic variables with or without SAE during reperfusion. We conclude that SAE (0.125 g/kg, 0.25 g/kg, and 0.5 g/kg) does not significantly affect myocardial stunning in conscious dogs. IMPLICATIONS: In contrast to previous experiments in anesthetized dogs, short-term administration of ethanol does not alter myocardial stunning in conscious dogs.
