Oxygen Free Radicals Enhance Ergonovine-Induced Canine Coronary Vasoconstriction
In order to examine the effects of oxygen free radicals on the ergonovine (EM)-induced coronary vasoconstriction in vivo, we administered EM (50 μg) into the ostium of the left coronary artery (LCA) and angiographically evaluated the change of diameter of the left anterior descending (LAD) and the left circumflex (LCX) coronary artery in eight dogs before and after selective administration of oxygen free radicals, generated by xanthine (X)-xanthine oxidase (XO) reaction, into the LCX. To investigate the participation of serotonin in EM-induced vasoconstriction, the concentrations of serotonin in the LCA and the coronary sinus (CS) were measured before and after administration of X - XO. The dlameter of the LCX remained essentially unchanged after administration of X + XO. However, EM-induced constriction was greater in the LCX than in the LAD. The difference of serotonin (S) concentrations in the CS and in the ostium of the LCA [(S in CS) - (S in LCA)] gradually increased after administration of X + XO. Electron microscopy of endothelial surface revealed marked changes in the LCX, but such changes were not observed in the LAD. These results suggest that the enhancement of the EM-induced vasoconstriction of coronary artery by oxygen free radicals may probably be due to the morphological change and the rise in the S produced by oxidative injury.
KeywordsLeft Anterior Descend Xanthine Oxidase Coronary Sinus Oxygen Free Radical Left Coronary Artery
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