DECREASED SULFHYDRYL-GROUPS IN THE REPERFUSED MYOCARDIAL TISSUE OF A RAT MODEL OF MYOCARDIAL-INFARCTION

The aim of this study was to determine whether myocardial injury resul ting from temporary ischemia followed by reperfusion can be measured b y assaying sulfhydryl groups in the affected tissue of a rat model of myocardial infarction. We studied 3 groups: a control group (n=6), whi ch underwent surgery without left coronary artery (LCA) ligation; grou p NoR (n=9), in which the LCA was ligated for 3 h; and group I+R (n=7) , in which 30 min LCA ligation was followed by 3 h reperfusion. The su lfhydryl group content of myocardial tissue was assayed by measuring t he fluorescence produced by incubating heart sections with N-(7-dimeth ylamino-4-methyl-3-coumarinyl) maleimide (DACM), which binds sulfhydry l groups. The fluorescence intensity (FI) of normal and infarcted myoc ardium was quantified by our computerized system of microscopic fluoro photometry. Indices such as sulfhydryl group content, the size of the low-FI area [%AREA(lower FI)] and the relative decrease in FI [%FI(dec rease)]) in the infarct zone were calculated. Both %AREA(lower FI) and %Fl(decrease) were significantly higher in the infarcted zone of anim als in NoR and I+R groups than in control animals. Both indices were h igher in infarct tissue from animals in the ISR group than in the NoR group. These changes suggest that sulfhydryl group content is signific antly reduced in tissue that has been subjected to ischemia-reperfusio n. Microscopic fluorophotometry, as defined by DACM staining of myocar dial tissue, may help to delineate areas of myocardial reperfusion inj ury.