Kinetic analysis of the uptake of fructose by erythrocytes. (A) Time course of the uptake of 0.5 mmol/L fructose. (B) Time course of the uptake of 0.5 mmol/L deoxyglucose. (C) Double-reciprocal plot of the substrate dependence for fructose transport. Uptake was measured in the presence of concentrations of fructose ranging from 3 to 40 mmol/L. (D) Semilog plot of the concentration dependence for inhibition of fructose transport by deoxyglucose. Measurements were performed at 0.5 mmol/L fructose using 1-minute uptake assays. (E) Semilog plot of the concentration dependence for inhibition of fructose (•) and deoxyglucose transport (○) by cytochalasin B. Measurements were performed at 0.5 mmol/L fructose or deoxyglucose using 1-minute uptake assays. Cells were preincubated for 5 minutes with cytochalasin B. Where appropriate, data represent the mean ± SD of at least four samples.