ENDOTHELIUM-DEPENDENT CORONARY FLOW IN ISCHEMIA-REPERFUSION

The aim of the present report was to study the effect of ischemia-repe rfusion on the endothelial cell function of coronary vessels. Twelve a dult male dogs were instrumented for the measurement of aortic and lef t ventricular pressures, heart rate and coronary blood flow. The left anterior descending coronary artery was occluded for 90 minutes follow ed by 20 minutes of reperfusion. Acetylcholine was infused into the co ronary artery at a rate of 15 mu g/kg/min. Coronary flow, heart rate a nd aortic and left ventricular pressures were registered during the pr e-occlusion period and after 20 minutes of reperfusion under basal con ditions, as well as during acetylcholine administration. These same pa rameters were also measured during reactive hyperemia following vessel deocclusion. Acetylcholine produced a 155 % increasing coronary flow during the pre-occlusion period (p < 0.05). In the reperfusion period, no statistically significant difference was observed between the flow s in the presence and absence of this substance, nor were there any di fferences in the other cardiovascular parameters monitored. Triphenylt etrazolium staining confirmed myocardial infarction in all the hearts examined. The authors conclude that reperfusion following myocardial i nfarction prevents the increasing in coronary flow in response to acet ylcholine as a result of endothelial dysfunction in the resistance cor onary vessels.