Fig. 3.

U50488- or Sal-A–mediated inhibition of PGE₂-stimulated cAMP accumulation in rat primary sensory neuron cultures. (A) Cells were treated with PGE₂ (1 µM) with or without U50488 or Sal-A (doses indicated) for 15 minutes. (B) Cells were pretreated with nor-BNI (3 nM, 15 minutes) or PTx (400 ng/ml, 24 hours) and then incubated with PGE₂ plus Sal-A (100 nM) for 15 minutes. Cellular levels of cAMP were measured with radioimmunoassay. Basal cAMP levels averaged 0.22 ± 0.03 pmol per well. Data are expressed as the percentage of PGE₂-stimulated levels, which averaged 217 ± 22% above basal levels and represent the mean ± S.E.M. of six experiments. ***P < 0.001 compared with vehicle (VEH) pretreatment.