BOVINE GLYCOGENOSIS TYPE II. BIOCHEMICAL AND MORPHOLOGICAL CHARACTERISTICS OF SKELETAL MUSCLE IN CULTURE

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Abstract
The biochemical and morphological properties of cultured skeletal muscle from calves born into a herd of cattle, which are heterozygous for glycogenosis type II, were studied over 17 days. Muscle was cultured by a modification of the explant technique in which the mononucleated cells that grew from the explants were subcultured. Skeletal muscle from animals up to 15 months of age grew in culture to produce mature, cross-striated and spontaneously contractile myotubes. The creatine kinase activity was 310 (±45.4) mU/mg protein on day 7 when fusion was complete, and 210 (±15.1) mU/mg protein on day 17 of culture. Mature muscle cultures from animals affected by glycogenosis type II showed the characteristic biochemical and morphological abnormalities previously observed in vivo. Acid α-glucosidase activity was absent whereas the activities of neutral α-glucosidase, lysosomal a-mannosidase and creatine kinase were the same as in cultures of unaffected muscle. The concentration of glycogen was higher in cultured affected muscle than in cultured unaffected muscle. On days 7, 9 and 17 of culture the glycogen concentrations were 66.7 (±2.7), 89.0 (±5.5) and 120.3 (±34.2) μg/mg protein respectively in affected muscle and 51.8 (±3.6), 59.9 (±5.4) and 55.4 (±1.0) μg/mg protein respectively in non-affected muscle. Electron microscopic studies showed that the glycogen accumulated within the lysosomes. These results indicate that bovine glycogenosis type II is expressed in tissue culture since the cultured skeletal muscle from affected animals shows the same abnormalities as skeletal muscle in vivo.