Intracellular distribution of some enzymes in the normal cardiac muscle and under the effect of thyroxine injection in adult albino rat

ABSTRACT

The present study was carried out on 32 adult male albino rats, eight of them were used as control and the rest were divided into three groups [eight rats each], that injected daily intraperitoneally with proper dose of thyroxine and sacrificed after 7, 10 and 15 days. The heart was removed and the left ventricle was examined histochemically for succinic dehydrogenase, alkaline phosphatase and acid phosphatase enzymes. Succinic dehydrogenase was found to be apparently strong in activity in the normal myocardium and were more distributed subsarcolemmally in the muscle fibers specially concentrated near the epicardium and subendocardium. Alkaline phosphatase was moderate in activity and were distributed equally in the sarcoplasm of the muscle fiber and specially strong around the blood vessels. Acid phosphatase was found to be weak in activity in myocardium and present in both sarcoplasm and nuclei. After thyroxine injection, there was progressive increase in succinic dehydrogenase activity [denoted increased aerobic oxidation], alkaline phosphatase [denoted increased demands for absorption of nutrient] and acid phosphatase [denoted cell injury and autolysis]. The distribution of the mentioned enzymes after thyroxine was found to follow the same manner as that of the control. Also, some areas of the myocardium showed more activity than the others i.e. Patchy in distribution