Free cytoplasmic Ca++ at rest and after cholinergic stimulus is increased in cultured muscle cells from Duchenne muscular dystrophy patients.

We used a fluorescent dye, quin 2, to measure intracellular free calcium ([Ca++]i) in cultured skeletal muscle cells and skin fibroblasts from five Duchenne muscular dystrophy (DMD) patients and from five controls. We observed an enhanced [Ca++]i level, at rest and after acetylcholine (ACh) stimulation, in DMD muscle cells, but we did not detect any difference between DMD and normal skin fibroblasts. The abnormally higher [Ca++]i transient induced by ACh suggests that it plays a critical role in muscle degeneration. The skin fibroblast results suggests that there is no generalized membrane defect.