SummaryTaurine and ß-alanine uptake kineiics were studied in cultured skin fibroblasts from 9 patients with Friedreich's Ataxia and 8 controls. No significant difference was observed. The data support the presence of normal ß-amino acid carrier protein in Friedreich's Ataxia cell membrane.

SUMMARY:Taurine and β-amino uptake in cultured skin fibroblasts proceeds through at least two distinct amino acid transport systems. The predominant Bamino acid uptake system which we refer to as the “Beta” system, incorporates taurine in a proportion of 95%, β-alanine in a proportion of 80% and does not incorporate β-amino-isobutyric acid. A second transport system for β-alanine seems to be operative in cultured skin fibroblasts and this system shares the characteristics of system “L” for branched-chain and ringside neutral amino acids. Results of ion depletion experiments, metabolic inhibition by drugs and blocking agents and previous kinetic studies of taurine and β-alanine uptake in cultured skin fibroblasts failed to disclose any major difference in β-amino acid transport between control individuals and patients with Friedreich's ataxia.

SummaryGlutamic and aspartic acid uptake was measured in skin fibroblasts from patients with Friedreich's Ataxia, dicarboxylic aminoaciduria, and normal individuals. The results showed no difference in uptake kinetics of either dicarboxylic amino acids between Friedreich's Ataxia and normal cells, but reduced uptake velocities in dicarboxylic aminoaciduria fibroblasts. Friedreich's Ataxia fibroblasts were, however, less calcium-dependant and more magnesium and phosphate-dependent than controls in glucose-free incubation mixture. This difference might be related to some degree of glucose intolerance by Friedreich's Ataxia fibroblasts in culture.

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