Measurement of intracellular amino acids in cultured fibroblasts.

Tissue culture is a valuable tool for the study of cellular amino acid metabolism. However, accurate measurement of intracellular amino acids is difficult. Cells must be washed to remove the culture medium which is rich in amino acids, a procedure which may result in the loss of intracellular amino acids. Collection of the cells of washing and amino acid measurement is further complicated by the adherence of cultured fibroblasts to the culture vessel surface. An uncomplicated, reliable method for the determination of the amino acid content of cultured human diploid fibroblasts is described. The intracellular levels of several amino acids determined by this method are markedly higher than previously reported levels.