Figure 3.

PSB 0739 inhibits ADP-induced BSM contraction with dose dependence. A) Representative traces of BSM responses to indicated pharmacological application. To avoid possible complication of adenosine receptor-mediated effect, BSM strips were pretreated with 2.5 μM of CGS 15943 in this experiment. Left trace is a 500 μM ADP-induced quick BSM contraction. Right trace indicates when pretreated with 25 μM PSB 0739, the 500-μM ADP-induced BSM contraction was abolished. B) Left trace is the control α,β-meATP-induced BSM contraction. Right trace indicates that pretreatment with 25 μM PSB 0739 does not abolish P2X₁ receptor-mediated BSM contraction, which is induced by 10 μM α, β-meATP. Right panel summarizes the data, which indicate the pretreatment of PSB 0739 only slightly inhibits α,β-meATP-induced BSM contraction (∼15%). This is possibly due to the involvement of P2Y₁₂R in normal BSM muscle tension development. C) Summary of force inhibition (peak force minus baseline) on ADP-induced contraction with increasing PSB 0739 concentrations. Right panel shows nonlinear regression of PSB 0739 dose and contraction force response using the GraphPad Prism dose-response-inhibition program. *P < 0.05. D) Normalized version of C, with each force change normalized as a percentage change (compared to 500 μM ADP response as 1) with increasing PSB 0739 concentrations. Right panel shows nonlinear regression of PSB 0739 dose and contraction force response using the GraphPad Prism dose-response-inhibition program. *P < 0.05.