Abnormality of 2-deoxyglucose uptake kinetics in fibroblasts at low concentrations

Abstract

2-deoxyglucose uptake rates at low sugar concentrations (less than 500 μM) appeared to be lower than those predicted by the Michaelis-Menten model which correctly described higher concentrations. This phenomenon which we will call concentration-dependent transport lag, was also observed for L-glucose uptake which suggest that this phenomenon is carrier-independent. A model involving the perimembrane space is developed which, for L-glucose, gives k 1 = 0.931 ± 0.072 × 10 −6 l. mg protein −1. minute −1, k 2 = 2.97 ± 0.19 × 10 −7 l. mg protein −1. minute −1 and So = 88,8 ± 4,3 μM; where k 1 is the diffusion constant in the cell membrane, k 2 is the diffusion constant in the perimembrane space and S o the sugar concentration required in the external medium in order to provide an équivalent sugar concentration in the transport carrier area.