Exchange of fluorinated glucose across the red-cell membrane measured by 19F-n.m.r. magnetization transfer.
The 19F n.m.r. spectrum of 3-fluoro-3-deoxy-D-glucose (3FG) in a red-cell suspension was observed to contain separate resonances from the intra- and extra-cellular populations of both the alpha- and beta-anomers. This phenomenon was used with an n.m.r. spin-transfer procedure to measure the rate of exchange of the anomers across the human red-cell membrane under equilibrium-exchange conditions at 37 degrees C. The beta-anomer crossed the membrane significantly more quickly than the alpha-anomer. At a total 3FG concentration of 9.3 mM; the first-order rate constants for the efflux of the alpha- and beta-anomers were 0.41 +/- 0.15 and 0.88 +/- 0.20 s-1 respectively. The measurable 3FG exchange was inhibited by 75 and 100% respectively by the glucose-transport inhibitors cytochalasin B and phloretin. Glucose inhibited the exchange of 3FG, and the results were consistent with glucose and 3FG binding to the hexose-transport protein with similar affinity.
Potts
J R
JR
Department of Biochemistry, University of Sydney, N.S.W.
Hounslow
A M
AM
Kuchel
P W
PW
D003837:Deoxy Sugars / Q000378:metabolism*; D003847:Deoxyglucose / Q000031:analogs & derivatives / Q000378:metabolism*; D004910:Erythrocyte Membrane / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy / Q000379:methods
D003837:Deoxy Sugars; C007253:3-deoxy-3-fluoro-D-glucose; D003847:Deoxyglucose