FIGURE 7.

ATA, 3013, and 3017 do not change cellular levels of basal ATP or (forskolin + isoproterenol)-stimulated cAMP levels. A, ATP levels in the presence of ATA, 3013, and 3017. ATP pools of P2Y₆-1321N1 cells were metabolically labeled by preincubation with [³H]adenine for 3 h. ATA (100 μm), 3013 (100 μm), or 3017 (100 μm) was then added, the incubation was terminated after 30 min, and [³H]ATP levels were quantified as described under “Experimental Procedures.” The results are means ± S.E. and are representative of results obtained in two independent experiments. B, (forskolin + isoproterenol)-stimulated cAMP accumulation in the presence of ATA, 3013, or 3017. [³H]Adenine-prelabeled P2Y₆-1321N1 cells were incubated with the indicated concentrations of ATA, 3013, or 3017 for 30 min prior to a 10-min challenge with 10 μm forskolin and 10 μm isoproterenol. Accumulation of [³H]cAMP was quantified as described under “Experimental Procedures.” The results are means ± S.E. and are representative of results obtained in two independent experiments. Basal cpm accumulation (data not shown) was ∼400 cpm for each condition and was not changed by the addition of ATA, 3013, or 3017 at concentrations up to 100 μm.