Glutamate uptake by rat hepatocytes in primary monolayer culture was found to be mediated by a Na+-independent and by two Na+-dependent transport systems of high and low affinity. Inhibition studies with cysteate and other model amino acids rules out the participation of the neutral amino acid transport systems A, ASC, and N and revealed that the Na+-dependent agencies represent unequivocally anionic transport systems. Na+-dependent uptake of glutamate in isolated hepatocytes was slow compared to the Na+-independent portion, but increased spontaneously during cultivation. In the presence of dexamethasone it was stimulated about 10-fold at the second day of cultivation.
