ABSTRACT
Myocardial injury was induced in 25 dogs by infusing isoprenaline, 2-4 microgram per kg per minute for the duration of six hours. 10 dogs served as controls which received only physiological saline. Animals receiving isoprenaline 2 microgram per kg per minute were labeled as experimental group A and other receiving microgram per kg per minute as experimental group B. Histopathological observations in experimental groups A and B showed subendocardial haemorrhage in the papillary muscles and apex of left ventricle as early as two-three hours of infusion. Focal lesions characterized by congestion, dilatation and extravasation of blood was observed near necrotic myocardium. Group A animals showed only severe tachycardia while in group B myocardial infarction in 80% and only ischaemic changes in 20% of animals were observed. Out of animals in group B, 37.5% developed myocardial infarction after two hours of infusion while remaining 62.5% developed changes after four hours. Histopathological changes were very well correlated with ECG findings observed in the present study