Figure 2.

Sulpiride, a D2/3R antagonist, reverses the inhibitory effect of dopamine on the UTP-evoked intracellular Ca²⁺ rise in type II cells. (A,D) Representative type I and type II cell traces showing the [Ca²⁺]_i response to UTP (100 µM), UTP + DA (10 µM), UTP + DA +,Sulpiride (SULP; 10 µM (A), 1 µM (D)), and UTP alone (after washout of DA and SULP). Note Sulpiride reversed the DA inhibition of UTP-evoked [Ca²⁺]_i response in the type II cell; the type I cell only responded to high K⁺. Summary data of the UTP-evoked integrated [Ca²⁺]_i (nM∙s) (B,E) and duration of the [Ca²⁺]_i responses (C,F) in type II cells before, during, and after exposure to DA, or DA plus Sulpiride (n = 3–5 dishes/group, 10–15 cells sampled per dish). In these experiments, 52 of the 101 cells showed both a reduction in the UTP-evoked response in the presence of DA and subsequent recovery of the response during co-application with Sulpiride. Data were analysed using a one-way repeated measures analysis of variance (ANOVA) followed by Tukey’s post hoc test; * signifies a p value of < 0.05. Values are means ± S.E.M.