Dose Response Study on Myocardial Injury Induced by Isoproterenol injection in Male Wistar Rats

Isoproterenol (ISO) is one of the chemicals that are widely used as an infarction-inducing agent. This study aimed to perform a dose response study on myocardial infarction induced by isoproterenol subcutaneous (s.c) injection in male Wistar rats. Rats were divided into five groups: healthy controls with no isoproterenol treatment and groups receiving subcutaneous (s.c) injection of isoproterenol at a dose of 85mg/kg, 120mg/kg, 150mg/kg, and 200mg/kg. Twenty-four hours following the injection, rat’s blood was taken through lateral veins to measure the CK-MB and LDH levels, the biomarkers of myocardial infarction. A necropsy was also performed to obtain the heart for histopathological examination. It was found that isoproterenol increased serum CK-MB and LDH levels. Moreover, histopathology examination showed a significant myocardial injury in groups treated with isoproterenol starting at the dose of 85 mg/kg. The severity of myocardial infarction intensified with the increase of dose. Mild to moderate injury was found in group treated with 85 mg/kg and 120 mg/kg, severe damage with 150 mg/kg and very severe damage was found in 200 mg/kg group. It is concluded that the s.c injection of ISO produced myocardial injury after 24 hours in rats in a dose response manner.