Normal and dystrophic hamster myoblasts and fibroblasts were compared for characteristic indicators of growth and differentiation. Clonal analysis of myoblast cultures indicated that 80% of colonies judged to be fusion-competent had differentiated. Dystrophic myoblasts were identical to normal in terms of their morphology, fusion potential (81.4%), and myokinase activity (59.6-49.1 mU/mg at 2-7 days), but displayed a significantly higher plating efficiency (normal: 52.6%; dystrophic: 82.1%), a longer doubling time (normal: 21.7 hours; dystrophic: 33.3 hours), and a lower day-7 creatine kinase activity (normal: 60.7 mU/mg; dystrophic: 41.3 mU/mg). Dystrophic fibroblasts were indistinguishable from normal ones in terms of their morphology, plating efficiency (90.4%), and doubling time (32.5 hours), but displayed a significantly lower day-2 creatine kinase activity (normal 58.3 mU/mg; dystrophic: 35.8 mU/mg) and day-7 myokinase activity (normal: 52.7 mU/mg; dystrophic: 39.9 mU/mg). The results are suggestive of an early and differential expression of the primary defect in dystrophic hamster myoblasts and fibroblasts in culture.
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