Transport of 1,5-anhydro-D-glucitol into human polymorphonuclear leukocytes

1,5-Anhydro-D-glucitol (AG) is one of the main polyols and its structure resembles glucose. It has been proposed that decreased serum AG concentrations in diabetic patients are a novel indicator of diabetic metabolic derangement. However, the pathway of AG metabolism still remains to be clarified. In this study we investigated the transport of AG into human polymorphonuclear leukocytes (PMNLs) isolated from healthy volunteers and found that 0.1 mM 3-O-methy-D-glucose (3OMG) was equilibrated with a half saturation time of 10 s, while the uptake rate of AG was much slower. The concentration dependence of AG uptake revealed that the AG transport velocity reached a plateau, with a Km of about 50 mM and Vmax of about 25 nmol/min/10(7) cells. Transport of 14C-labeled 3OMG was inhibited by unlabeled D-glucose or AG in a dose-dependent manner. The mean inhibition constant (Ki) for D-glucose and for AG were 1.06 and 4.93 mM, respectively. Cytochalasin B (20 microM) inhibited 3OMG transport by 90% but AG transport by only 50%. S/V for 14C-labeled AG transport plotted against the concentration of unlabeled 3OMG showed a non-linear and biphasic pattern. These results suggest that AG influx into PMNLs is mediated not only by the cytochalasin B-sensitive glucose transport system but also via another facilitated transport system.