Related Experiment Video
Updated: Aug 12, 2026

Extracellular Glucose Depletion as an Indirect Measure of Glucose Uptake in Cells and Tissues Ex Vivo
Published on: April 6, 2022
High- and low-affinity transport of D-glucose from blood to brain
Abstract:
Measurements of the unidirectional blood-brain glucose flux in rat were incompatible with a single set of kinetic constants for transendothelial transport. At least two transfer mechanisms were present: a high-affinity, low-capacity system, and a low-affinity, high-capacity system. The low-affinity system did not represent passive diffusion because it distinguished between D- and L-glucose. The Tmax and Km for the high-affinity system were 0.16 mmol 100 g-1 min-1 and 1 mM; for the low-affinity system, approximately 5 mmol 100 g-1 min-1 and approximately 1 M. With these values, physiological glucose concentrations were not sufficient to saturate the low-affinity system. In normoglycemia, therefore, three independent pathways of glucose transport from blood to brain appear to exist: a high-affinity facilitated diffusion pathway of apparent permeability 235 X 10(-7) cm s-1, a specific but nonsaturable diffusion pathway of permeability 85 x 10(-7) cm s-1, and a nonspecific passive diffusion pathway of permeability 2 x 10(-7) cm s-1.
More Related Videos
07:18Visualizing Monocarboxylates and Other Relevant Metabolites in the Ex Vivo Drosophila Larval Brain Using Genetically Encoded Sensors
Published on: October 27, 2023
07:04Measuring Uptake of the Glucose Analog, 6-(N-(7-Nitrobenz-2-Oxa-1,3-Diazol-4-yl)Amino)-6-Deoxyglucose, in Intact Murine Neural Retina
Published on: March 14, 2025
Related Concept Videos
Secondary Active Transport
Membrane Proteins
Secondary Active Transport
Transcellular Transport of Solutes
Glucose Transporters
Facilitated diffusion-glucose transporters (GLUTs) are encoded by the solute-linked carrier (SLC) family 2, subfamily A gene family, or SLC2A. The 14 GLUT protein members are distributed into three classes:
Glucose Absorption Into the Small Intestine