Electrical and mechanical activity of myocardium in mice with muscular dystrophy

¹ Department of Medicine, New York University College of Medicine; and Electrocardiographic Laboratory of the Third (N.Y.U.) Medical Division of Bellevue Hospital, New York City

The intracellular potential and maximum tension output of the atrial and ventricular myocardium of dystrophic mouse, strain 129, developed at Jackson Memorial Laboratory, showed no significant differences from normal littermate. Histological sections of these tissues stained by hematoxylin and eosin revealed no morbid changes. By contrast, the gastrocnemius muscle of the dystrophic strain revealed a significantly decreased maximum tension output and marked prolongation of the relaxation period when compared to that of a normal mate. Histological sections of the gastrocnemius muscle of the dystrophic mate showed variable degrees of morbidity. The absence of significant differences in the electrical and mechanical parameters of the myocardium in the normal and genetically dystrophic littermate indicates that the myopathic process spares the cardiac muscle. This is at variance with the picture seen both in rats reared on a prolonged vitamin E deficient diet and in the progressive form of human muscular dystrophy where morbid changes involving the myocardium are rather frequent.