ISSN:
1471-4159
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
Abstract— —The uptake of the glucose analogue 2-deoxy-d-glucose by rat brain cortex slices was studied in order to compare the rate of membrane transport with the rate of phosphorylation in the concentration range 5–12 mM-glucose plus 0.5–15 mM-2-deoxy-glucose. The comparison was carried out by fitting a model of the brain slice to uptake data and by determination of 2-deoxy-glucose and 2-deoxy-glucose-6-phosphate by ion exchange chromatography.The rate of membrane transport exceeded the rate of phosphorylation by at least one order of magnitude. The membrane transport was so rapid that the extracellular diffusion became rate limiting for the uptake. The membrane transport could therefore only be determined as a minimum value and it was not possible to determine unidirectional flux across the cell membranes (initial rate). Accordingly, characterization of the membrane tranport with respect to maximal transport rate and affinity was not possible. The phosphorylation reaction, however, was so slow that it was accessible for exact determination and only the phosphorylation reaction was responsible for the fact that the cellular uptake of 2-deoxy-glucose was of the Michaelis-Menten type, thus emphasizing the importance of dissociation between membrane transport and metabolism when transport is studied of a substance which can undergo metabolism.The data indicate that glucose transport across glial and neuronal membranes is not rate limiting for glucose metabolism of brain tissue in vitro.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1471-4159.1977.tb09610.x
