On the role of mitochondria in the hereditary cardiomyopathy of the Syrian hamster.

Conventional polarographic techniques reveal no defect of oxidative phosphorylation in cardiomyopathic hamster heart mitochondria. However, in skeletal muscle of the same animals a defect is seen consistently with NAD+-linked substrates. This mitochondrial defect is caused by calcium accumulation and a consequent loss of NAD+ and magnesium. As shown by density gradient centrifugation, the defect resides in only a small fraction of all mitochondria. It is assumed that the same genetic defect in BIO 14.6 hamsters causes both skeletal muscle and heart lesions. Calcium levels in heart mitochondria are also significantly elevated in heart mitochondria. It is postulated that a calcium-associated defect similar to that in skeletal muscle mitochondria exists also in a very small fraction of the heart organelles and is responsible for the occurrence of focal necrosis.