Electrolysis-induced myocardial dysfunction : A novel method for the study of free radical mediated tissue injury

Abstract

Oxygen-derived free radicals and other oxidizing species are thought to be involved in inflammation and ischemic tissue injuries. Recently, oxygen-derived free radicals also have been implicated in tissue injury of the myocardium subjected to ischemia/reperfusion. The purpose of this investigation was to determine if electrolysis of a physiological buffer would serve as a source of free radicals, and if these radicals would lead to alterations in myocardial function. Isolated Langendorff-perfused rabbit hearts perfused with buffer subjected to a 20 mA D.C. current for 2 min demonstrated significant increases in coronary perfusion pressure (37 +/- 6 mmHg), left ventricular end diastolic pressure (41 +/- 7 mmHg), and loss in left ventricular developed pressure (35 +/- 5%). The free radical scavengers, Superoxide dismutase and a combination of tryptophan plus glycine, were effective in protecting the hearts from the effects of electrolysis. The presence of free radicals was semiquantitated with a radical-luminol chemiluminescent assay. In this assay a variety of radical scavengers and antioxidants were effective (i.e., dimethyl sulfoxide, nitro blue tetrazolium, ascorbate, superoxide dismutase, 1, 3-diphenyisobenzofuran, and glycine, catalase), whereas mannitol and tryptophan were not effective. The data indicate that electrolysis of a physiological buffer produces a milieu containing several reactive oxygen species or free radicals that have the potential to produce alterations in a biological system. This method has the advantage over existing protocols for the generation of radicals in that it is a blood-free and an enzyme-free system.