We investigated several amino acids and carnitine transport activities of bovine mammary gland epithelial cells. Gly, Ala, Gln, Glu, Arg, Leu, cystine and carnitine transport activities at 1 μmol/L substrate concentration were 24.0 ± 3.97, 90.9 ± 13.4, 32.5 ± 9.0, 14.2 ± 5.1, 48.9 ± 11.4, 48.8 ± 5.1, 22.7 ± 6.8 and 2.56 ± 0.96 nmol/mg protein/min, respectively. Na-dependency of transport was observed in Gly, Ala and Gln, but not in Arg, Leu and carnitine. Glu and Cys transport activity without Na condition were reduced to 36%, 63% in Na-free condition, respectively. Carnitine transport activities were low but detectable with or without Na condition. There was no correlation between amino acid transport activities and their concentrations in milk. The data clarified in this paper will be basic data for metabolic analysis of bovine mammary gland
