[Qualitative and quantitative histoenzymatic study on isoproterenol induced myocardial necroses in rats (author's...

By means of a 2-day s.c. application of 60 mg/kg isoproterenol in Wistar rats reproducible myocardium necroses with a characteristic topography were induced. The lesions were particularly found in the sub-endocardial area, penetrating intramurally into the wall of the left ventricle and spreading to the papillary muscle, the area of the apex of the heart, and they also appeared in the neighbourhood of the coronary arteries. The quantitative and qualitative histo-enzymatic determinations of the activity of oxydative mitochondrial enzymes, cytochromoxydase and succinatedehydrogenase do not only show a marked decrease of activity in the area of lesions proved by histopathological investigations, but also very sensitively demonstrate a beginning myocardial hypoxia in such areas which in histopathological tests only show light to medium infiltrations and above that also signify clearly that in the neighbourhood of the lesions a compensatory increase of the oxydative metabolism is found. The possibility of using myocardial necroses in rats, induced by the application of isopreterenol, as a model for the experimental study of new heart and coronary drugs, is discussed.