FIGURE 1

Effect of C₆-ceramide on the stimulation of 2-deoxyglucose transport by insulin. Differentiated 3T3-L1 adipocytes were incubated in DMEM supplemented with 10% foetal bovine serum (), or the medium containing 100 M C₆-ceramide () for 4 h. Cells were then incubated in DMEM containing 0.5% BSA (w/v) with or without ceramide for 2 h. After washing twice with Krebs-Ringer phosphate buffer, cells were exposed to 0–1000 nM insulin for 30 min. Glucose uptake was measured by adding 0.1 mM 2-[³H]deoxyglucose (0.5 Ci/35 mm dish). After incubation for 10 min, the medium was withdrawn and the cells were washed three times with ice-cold Krebs -Ringer phosphate buffer. Glucose transport was calculated from the radioactivity taken up by the cells (A). Insulin-dependent glucose transport was calculated as the difference between glucose uptake in the presence and absence of insulin (B). Results are meanss.d. (where large enough to be shown) of duplicate determinations from three independent experiments. Significant differences between control and ceramide-treated cells are indicated by *P<0.05, **P<0.01 and ***P<0.001.