Abnormal Electrical Activity Induced by H2O2 in Isolated Canine Myocytes
Free oxygen radicals may participate in a variety of pathological cardiac conditions which are associated with an increased incidence of arrhythmias. For example, adriamycin, an anti-cancer agent that undergoes redox-cycling and produces radicals, causes arrhythmias that restrict its therapeutic usefulness.1 The arrhythmias that accompany reperfusion of ischemic hearts are reduced by the presence of allopurinol2 or free radical scavengers3,4 and enhanced by Fe-ADP4. Such reports imply that radicals have a direct effect on the electrical activity of myocardial cells. Yet this indirect evidence is weak because it relies on the production of radicals during pathological conditions which simultaneously produce hypoxia, acidosis, hyperkalemia or other biochemical changes. Previously, we have described a distinct sequence of electrophysiological changes that occur in the presence of free-radical-generating systems consisting of 3 mM dyhydroxyfumaric acid or xanthine:xanthine oxidase.5,6 The changes induced by exogenous generating systems follow a reproducible pattern. They are not readily reversed by removal of the generating system but can be partially prevented by the addition of the free radical scavengers superoxide dismutase and catalase.6 The generating systems used previously should produce a spectrum of free radicals in our superfusion solutions, but they also require the addition of one or more compounds to the superfusate.
KeywordsXanthine Oxidase Action Potential Duration Plateau Voltage Upstroke Velocity Partial Depolarization
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- 5.P.L. Barrington, C.F. Meier, Jr., and W. B. Weglicki, Effect of free radicals on the canine myocyte action potential, Fed. Proc. 44:1578 (1985).Google Scholar
- 6.P.L. Barrington, C.F. Meier, Jr., B. F. Dickens, and W. B. Weglicki, Free radical scavengers protect canine myocytes from radical-induced changes in the action potential, Circ. 72 (suppl III):228 (1985).Google Scholar