Electron microscopic study of the effect of theophylline on the myocardium of albino rat

ABSTRACT

Theophylline intoxication is one of the most common causes of both acute toxicity and chronic unintentional overmedication. The possible toxic effects of theophylline on the ultrastructure of the myocardium have been studied in this current experiment. Two groups of male adult albino rats were used in this study. The first group served as control. The rats of the second group received intraperitoneal injection of theophylline at a dose of 100 mg/kg/day for 5 days. All animals were sacrificed in the 6th day and parts of the myocardium were quickly removed and processed for electron microscopic study. The results showed that theophylline led to multiple ultrastructural changes of the myocardium in the form of myofibrillar degeneration, mitochondrial degeneration, intracellular fluid accumulation and intercalated discs degeneration. Myofibrillar degeneration, mitochondrial degeneration and intracellular fluid accumulation could be considered as ischemic changes. The destruction of the intercalated discs indicates dysfunction in both cardiomyocytes conductivity and contractility. It is concluded that theophylline, the worldwide used bronchodilator, can cause damage to the myocardium at subcellular level. This leads to the recommendation of respecting different factors which can increase the drug safety including limitation of its use only when indicated, proper calculation of its dose and avoiding drug-drug interaction which may increase the possibility of theophylline toxicity