Muscle cell cultures in Menkes' disease: Copper accumulation in myotubes

We present 64Cu uptake studies in cultured muscle cells from a one-year-old patient with Menkes' disease. The cultured muscle cells from the patient showed a five-fold higher 64Cu uptake than control muscle cells. Copper uptake in muscle cells was of the same magnitude as that found in fibroblasts from the patient and also from other Menkes' patients. The copper content of a muscle biopsy from the patient was twice that of a control biopsy. The enhanced uptake is probably copper specific, since zinc uptake was unaltered in both muscle cells and fibroblasts from the patient. Cytochrome c oxidase in the muscle of the patient was reduced to one-third of the value for controls, which is in agreement with the hypothesis that in Menkes' disease copper accumulates in a biologically non-active form. However, in cultured muscle cells and fibroblasts from the patient the cytochrome c oxidase activity was in the normal range, probably because of the relatively large amount of copper already available in the culture medium.