Figure 5.

Effect of pertussis toxin on the UTP or ATPγS-induced accumulation of InsP₃ in 1321N1 cells expressing the human P2Y₂ C variant (similar results were obtained with the R variant). The cells were preincubated or not overnight in the presence of 100 ng ml⁻¹ of pertussis toxin (PTX) and were then incubated in the presence of various concentrations of UTP or ATPγS for 30 s (A) or 15 min (B). The data represent the mean±s.d. of triplicate points and are representative of three independent experiments. The EC₅₀ values (means±s.e.mean) shown in the inset were calculated on basis of the three experiments.