Glucose transport and utilization in the human brain: model using carbon-11 methylglucose and positron emission tomography.
3-0-[11C]-Methyl-D-glucose (CMG) is specifically suited for measuring carrier facilitated glucose (G) transport; it enters the free G pool in tissue from where it is not utilized for metabolism in contrast to G, but is transported back into circulation. The ratio of carrier affinity for G and CMG was reported to be 1.11. By simultaneously measuring CMG concentration in plasma and in cerebral cortex in vivo with positron tomography at 1-min intervals for 40 min, two time-activity curves are obtained, as reported previously, which together with the G concentration in plasma yield the in vivo rate constants of G transport across the blood-brain barrier and the rate of G inflow; a repeat measurement at a different G concentration in plasma gives the in vivo Michaelis-Menten constant KM and the maximal rate of transport VMAX. The present paper summarizes and extends this approach to analyzing the free G pool in tissue, the rate of G return to circulation, and the rate of G exit into metabolism with its corresponding rate constants. The data from six volunteers agreed with results reported for the individual biochemical parameters in primate brains.
D019325:3-O-Methylglucose; D001786:Blood Glucose / Q000032:analysis; D001812:Blood-Brain Barrier; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism*; D002250:Carbon Radioisotopes / Q000378:metabolism; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008433:Mathematics; D008757:Methylglucosides / Q000097:blood / Q000378:metabolism; D008759:Methylglycosides; D008954:Models, Biological; D014055:Tomography, Emission-Computed
D001786:Blood Glucose; D002250:Carbon Radioisotopes; D008757:Methylglucosides; D008759:Methylglycosides; D019325:3-O-Methylglucose; D005947:Glucose