Normal pyruvate oxidation in Friedreich ataxia and Charcot-Marie-Tooth disease fibroblasts

Partial defects in activity of the pyruvate dehydrogenase complex have been described by some investigators in cell lines from Friedreich ataxia and Charcot-Marie-Tooth disease patients. Methylene blue was used to stimulate the rate of pyruvate oxidation in two different assay systems of pyruvate dehydrogenase activity in cultured human fibroblasts to determine if such partial defects, if present, could be detected in a stimulated assay system. Cell lines from normal controls, five patients with Friedreich ataxia, six related persons with Charcot-Marie-Tooth disease patients were studied. Although methylene blue (at a concentration of 25 mumol/l) significantly increased pyruvate oxidation in both assay systems and in all cell lines studied, no significant differences in pyruvate oxidation could be demonstrated between the control cells and either the Friedreich ataxia or Charcot-Marie-Tooth cell lines.