FIGURE 6.

Concentration-dependent inhibition of receptor-promoted inositol lipid signaling by ATA, 3013, or 3017. A, P2Y₆-1321N1 cells metabolically prelabeled with [³H]inositol were incubated with increasing concentrations of ATA, 3013, or 3017 for 1 h before stimulation with UDP (100 μm). The cells were lysed, and the radioactivity of the lysate was quantified as described under “Experimental Procedures.” The experiment was repeated three times. B, as described for A, HEK293A cells were metabolically prelabeled with [³H]inositol and treated with increasing concentrations of the inhibitors before incubation with carbachol (10 μm) and quantification of radioactivity. C, the IC₅₀ values for ATA, 3013, and 3017.