Cardiomyopathy of hamster dystrophy.

Investigations of the fine structural changes observed in the hearts of cardiomyopathic hamsters at very early stages of the disease indicate that the initial changes involve the pericapillary mesenchymal cells. Other prominent features consist of hypercontraction of cardiocytes, disruption of intercalated disks, and eventual partitioning of cardiac cells, with myofibrillar lysis. The generalized plasma membrane defect allows a net increase in calcium influx and a depression in mitochondrial respiratory control ratios. These pathologic events are in accord with previously reported increases in myocardial sympathic nerve activity.