Counter transport of glutamine and choline in cultures of human glioma cells.

Tritiated glutamine and choline were released from human glioma cells in culture when incubated in permeant-free solution. Counter transport experiments revealed that the two neurotransmitter precursors were taken up and released by facilitated diffussion transport systems. It is suggested that glial cells $\text{in}\text{vivo}$ can provide neurons with glutamine and choline for transmitter synthesis via such systems.