Hepatocytes isolated from fed rats were used to investigate glutamine transport. Glutamine transport appears as a composite process involving at least two saturable components. The Na+-dependent component probably represents the entry through the N system. The Na+-independent component was also inhibited by histidine and exhibited trans-stimulation, suggestive of a facilitated diffusion process. Kinetic parameters for both systems suggest that facilitated diffusion only plays a minor role in glutamine influx. In contrast, the Km for glutamine efflux was consistent with a physiological role of the facilitated-diffusion component in glutamine release. In Na+ medium, relatively constant distribution ratios (about 8) between intra- and extra-cellular concentrations were observed, with external glutamine ranging from 0.5 to 5 mM. The present observations suggest that glutamine influx might largely be mediated by the N system, whereas facilitated diffusion allows hepatocytes to release glutamine when intracellular concentrations are elevated. The physiological consequences of this bidirectional transfer of glutamine across the liver cell membrane is discussed.
Research Article|November 15 1983
Bidirectional transport of glutamine across the cell membrane in rat liver
; ; ;
Biochem J (1983) 216 (2): 401-408.
- Views Icon Views
- PDF LinkPDF
- Share Icon Share
- Cite Icon Cite
P Fafournoux, C Demigné, C Rémésy, A Le Cam; Bidirectional transport of glutamine across the cell membrane in rat liver. Biochem J 15 November 1983; 216 (2): 401–408. doi: https://doi.org/10.1042/bj2160401
Download citation file: