Figure 4.

Effect of PKA inhibitor H-89 on secretin-stimulated cyclic AMP accumulation in NG108-15 cells. (A) Cells were treated with or without 10 μM H-89 for 30 min prior to and during addition of 100 nM secretin. Cyclic AMP accumulation was measured at the time-points indicated. Data are mean±s.e.mean (bars) from four separate experiments, each performed in triplicate. Over time, secretin-stimulated cyclic AMP accumulation was significantly increased in the presence of H-89 when compared with control (P=0.0003, two-way ANOVA). (Inset) Concentration-dependence of H-89-mediated increase in secretin-stimulated cyclic AMP accumulation, with calculated EC₅₀ of 19.8±6.1 nM. Cyclic AMP accumulation was measured after 60 min of secretin stimulation and expressed as a per cent of control 100 nM secretin response. Data are mean±s.e.mean (bars) from four separate experiments, each performed in quadruplicate. (B) Cells were treated with 10 μM H-89 or vehicle for 30 min prior to co-addition of secretin at concentrations stated for 60 min. Data are mean±s.e.mean (bars) from four separate experiments, each performed in triplicate.