Potential roles of myoglobin autoxidation in myocardial ischemia-reperfusion injury

The source(s) of reactive partially reduced oxygen species associated with myocardial ischemia/reperfusion injury remain unclear and controversial. My oglobin has not been viewed as a participant but is present in relatively h igh concentrations in heart muscle and, even under normal conditions, under goes reactions that generate met (Fe3+) species and also superoxide, hydrog en peroxide, and other oxidants, albeit slowly. The degree to which the dec rease in DW and the freeing of copper ions, as well as the variations in pO (2) associated with ischemia and reperfusion increase the rates of such myo globin reactions has been investigated. Solutions of extensively purified m yoglobin from bovine heart in 50 mM sodium phosphate buffer were examined a t 37 degrees C. Sufficiently mart;ed rate increases were observed to indica te that reactions of myoglobin can indeed contribute substantially to the o xidant stress associated with ischemia/reperfusion injury in myocardial tis sues. These findings provide additional targets for therapeutic interventio ns. (C) 1999 Elsevier Science Inc.