Kinetic validation of 6-NBDG as a probe for the glucose transporter GLUT1 in astrocytes
Article first published online: 7 APR 2009
© 2009 The Authors. Journal Compilation © 2009 International Society for Neurochemistry
Journal of Neurochemistry
Special Issue: The Third ISN Special Neurochemistry Conference/8th International Meeting for Brain Energy Metabolism “Neurodegeneration and Regeneration”
Volume 109, Issue Supplement s1, pages 94–100, May 2009
How to Cite
Barros, L. F., Bittner, C. X., Loaiza, A., Ruminot, I., Larenas, V., Moldenhauer, H., Oyarzún, C. and Alvarez, M. (2009), Kinetic validation of 6-NBDG as a probe for the glucose transporter GLUT1 in astrocytes. Journal of Neurochemistry, 109: 94–100. doi: 10.1111/j.1471-4159.2009.05885.x
- Issue published online: 7 APR 2009
- Article first published online: 7 APR 2009
- Received December 2 2008; revised manuscript received December 3 2008; accepted December 9 2008.
- cytochalasin B;
- kinetic analysis;
- mathematical modeling;
- numerical simulation
In recent years, the use of fluorescent glucose analogs has allowed the study of rapid transport modulation in heterogeneous cell cultures and complex tissues. However, the kinetic behavior of these tracers is not conventional. For instance, the fluorescent glucose analog 6-NBDG permeates the cell 50–100 times slower than glucose but the uptake of 6-NBDG is almost insensitive to glucose, an observation that casts doubts as to the specificity of the uptake pathway. To investigate this apparent anomaly in cultured astrocytes, which are rich in the glucose transporter GLUT1, we first estimated the kinetic parameters of 6-NBDG uptake, which were then incorporated into the kinetic model of GLUT1. The main outcome of the analysis was that 6-NBDG binds to GLUT1 with 300 times higher affinity than glucose, which explains why its uptake is not efficiently displaced by glucose. The high binding affinity of 6-NBDG also explains why cytochalasin B is less effective at inhibiting 6-NBDG uptake than at inhibiting glucose uptake. We conclude that 6-NBDG, used at low concentrations, permeates into astrocytes chiefly through GLUT1, and advise that the exofacial GLUT1 inhibitor 4,6-ethylidine-d-glucose be used, instead of glucose, as the tool of choice to confirm the specificity of 6-NBDG uptake.