Studies of sarcolemmal integrity in myopathic muscle

Studies of sarcolemmal integrity with extracellular Procion Yellow gave evidence of structural defects in a high percentage of muscle fibers in Duchenne dystrophy and in vitamin E-deficiency myopathy in the guinea pig. The dye entered fibers in these conditions more often than in controls. Myofibrillary clumping occurred in the region of major penetration of the dye. It seems likely that sarcolemmal defects occur in vivo in these conditions, allowing the entry of high concentrations of calcium into the sarcoplasm with consequent fiber damage. The biochemical basis of these sarcolemmal defects remains to be elucidated. Our procedure for biopsy of the vastus medialis muscle may prove useful in preparing a limb muscle for in vitro physiologic studies.