Emetine-induced cardiomyopathy in rabbits.

A correlative electrocardiographic and ultrastructural study of myocardium in rabbits, administered 1 mg/kg of emetine hydrochloride intramuscularly for 5 successive days of a week over 2 to 4 week period, was conducted. The study revealed electrocardiographic changes and a spectrum of ultrastructural lesions involving myocardial cells and interstitial neural elements. The severity of these lesions was related to the cumulative dose of the drug. Myocardial cell lesions were characterized by fatty infiltration, increase in glycogen content, myofibrillolysis, focal cytoplasmic degeneration, contraction-band necrosis and intercalated disc disjunction, herniation and fragmentation of the close junction (nexus). Neural lesions included mesaxonal and axonal myelinoid bodies and alterations in dense-core vesicles of biogenic amine containing cells. Atrial myocardial lesions were relatively fewer and less severe than those in the ventricular myocardium. The myocardial cell and neural lesions may be inter-related and underlie the pathogenesis of emetine-induced cardiomyopathy.