FIGURE 6.

AEA and 2-AG competition for the cellular uptake in U937 cells. A, concentration-dependent cellular [³H]AEA uptake inhibition and extracellular [³H]AEA accumulation after 5-min incubation of 100 nm [³H]AEA plus AEA in the presence of different concentrations of 2-AG (0.01–5 μm) in U937 cells (10⁶ cells). B, intracellular and extracellular AEA levels measured by CG/MS after a 5-min incubation with 100 nm AEA in the presence of different concentrations of 2-AG (0.1–5 μm) in U937 cells (10⁶ cells). C, concentration-dependent cellular [³H]2-AG uptake inhibition and extracellular [³H]2-AG accumulation after a 5-min incubation of 1 μm [³H]2-AG plus 2-AG in the presence of different concentrations of AEA (0.01–10 μm) in U937 cells. D, intracellular and extracellular 2-AG levels measured by CG/MS after a 5-min incubation with 1 μm 2-AG in the presence of 0.1–10 μm AEA in U937 cells (10⁶ cells). The values are expressed as a percentage of cellular and extracellular [³H]AEA or [³H]2-AG levels as compared with vehicle-treated control. For the absolute endocannabinoid quantification, the values are expressed as pmol of AEA or 2-AG/10⁶ cells. Data show mean values ± S.E. (error bars) of three independent experiments, each one carried out at least in triplicate. *, p < 0.05; **, p < 0.01, treated versus vehicle-treated control.