RESUMEN
Abuse of methamphetamine has become a major world-wide health problem. Because of the limited work that had been done looking at the cellular toxicity of methamphetamine and because its cardiotoxicity is not experimentally well documented. The present work was conducted to study the effects of chronic administration of methamphetamine, as well as the effect of withdrawal on the cardiac muscle of albino rats using histological and ultrastructural examination. This study was conducted on 60 adult male albino rats. They were divided into three equal groups. Group I was used as control. Group II received daily subcutaneous injection of 1mg/kg body weight of methamphetamine hydrochloride for 8 weeks. The third group received the same daily dose of methamphetamine hydrochloride for the same duration then, the treatment was discontinued for the next 4 weeks. At the end of the experiment rats were sacrificed and specimens from the heart were taken and were subjected to light and electron microscopic study. Two degrees of myocardial lesions were revealed on examination of the chronic toxicity group ranging from wavy muscle fibers with deeply stained nuclei up to sarcolemmal rupture and extrusion of the organelles. Mitochondrial swelling with focal cristal loss was also revealed. After drug withdrawal, there was reversal of most of myocardial lesions depicted in the chronic toxicity group except for excessive fibrous tissue deposition. Chronic methamphetamine administration brings about various myocardial lesions. However, most of these lesions are reversible after drug withdrawal