Figure 2.

Glutamate uptake inhibition is not eliminated in S1P₃-null and astrocyte-specific (As)-S1P₁/S1P₃-double-null astrocytes. Primary astrocytes from As-S1P₁, S1P₃, and As-S1P₁/S1P₃ receptor-null mice were incubated with labeled glutamate and S1P for 1 h at 37°C. A, Glutamate uptake in As-S1P₁^−/− astrocytes exhibited a slight left shift (decrease in glutamate uptake) compared with littermate controls. S1P₃^−/− (B) and As-S1P₁/S1P₃^−/− (C) astrocytes exhibited control levels of glutamate uptake. Data in each panel are from three independent experiments. Curve fitting was performed by nonlinear regression.