Abstract
Biochemical Studies of myocardial lesions induced by isoproterenol (ISP) were performed on the changes of myocardial water content, high energy phosphate levels and plasma enzyme activities. Protective effects of propranolol and anti-inflammatory drugs on the biochemical shifts by ISP were also examined. Cardiac water content increased immediately after subcutaneous injection of ISP and reduced near the normal level after 3 days. Anaerobic glycolysis and depletion of high energy phosphates were observed immediately after an injection of ISP. These biochemical shifts returned to normal within 24 hr except adenosine triphosphate (ATP) and total adenine nucleotide levels which remained at lower levels than normal. Distinct indications of returns toward the normal values with the levels of ATP and total adenine nucleotides took place at the same time as water content reduced. Plasma creatine phosphokinase (CPK), glutamic oxaloacetic transaminase (GOT) and lactic dehydrogenase (LDH) activities were markedly elevated after the treatment of ISP and did not reach to normal after 24 hr. Pretreatment with propranolol blocked the biochemical shifts by ISP, such as cardiac edema, depletion of myocardial adenine nucleotides and elevation of plasma LDH activity. Prednisolone or indomethacin pretreatment decreased the water content and plasma LDH activity, but did not show the influence on cardiac adenine nucleotide levels.
