Figure 1. The effects of ATP and purinergic receptor antagonists on I_mVDCC.

Bath and pipette contained 5 mm Ba²⁺ external and Cs⁺ internal solutions, respectively. A, time course of the effects of 100 μm ATP on I_mVDCC (•) and holding current. 100 ms depolarizing pulses to 0 mV (V_T) from a holding potential of −60 mV (V_h) were applied at an interval of 20 s. B, leak-subtracted traces of I_mVDCC in the presence of 10 μmα,β-methylene ATP (α,β-mATP, left) or 100 μm suramin (right) with or without 100 μm ATP. C, summary of the effects of pretreatment with α,β-mATP (10 μm), PPADS (10 μm) and suramin (100 μm) on ATP (100 μm)-induced potentitation of I_mVDCC. Columns and bars indicate means ±s.e.m. from 4–5 experiments. *, ** Statistically significant difference (P > 0.05 and 0.01, respectively) from the control value (dotted line). NS (not significant) and P values in the figure indicate the results of one way ANOVA and pooled variance t test.