Glucose transport in human erythrocytes measured using 13C NMR spin transfer

Abstract

We present the results of a new NMR-based procedure for measuring the fast transmembrane exchange of D-[1- 13C]glucose in human erythrocytes. The method relies on different rates of exchange between the α- and β-anomers of glucose inside and outside the cells; the rate outside the cells is greatly increased by the addition of mutarotase to the suspension. Theory is developed to describe nuclear-spin transfer in the present system and is used to analyse the data to yield estimates of transmembrane-exchange rate constants and their statistical uncertainties. For a total glucose concentration of 25.5 mmol/1 at 40°C the first order efflux rate constants for the α- and β-anomers were 1.20±0.40 s −1 and 0.71±0.30 s −1, respectively.