Quantitative measurement of [3H]ouabain binding to human skeletal muscle cryostat sections

The etiopathogenesis of myotonic muscular dystrophy is thought to involve a basic defect in muscle membrane. Biochemical investigations of human muscle membrane have been hampered by difficulty in obtaining large quantities of muscle at biopsy for the preparation of sarcolemma. We have determined [3H]ouabain binding to normal and myotonic dystrophy human skeletal muscle by using cryostat sections. The binding increased with increase in number of tissue sections (protein) and in concentrations of [3H]ouabain, ATP and Na+. The binding of [3H]ouabain in myotonic dystrophy patients was 2-3 fold higher than in normal and disease controls. Kinetic analysis revealed that the increased binding of ouabain to myotonic tissue sections was independent of low-affinity sites directed by ATP and Na+. These findings provide further evidence for the involvement of membrane abnormalities in myotonic muscular dystrophy.