Figure 4.

Effect of 100 μM inosine on VGCCs associated with spontaneous ACh secretion. (A) The universal VGCC blocker Cd²⁺ (100 μM, n = 4) diminished MEPP frequency and prevented the effect of inosine. (B) The L-type VGCC blocker nitrendipine (5 μM, n = 4) decreased spontaneous secretion and prevented the effect of inosine. (C) Nitrendipine had no effect when preparations were pre-incubated with inosine (n = 3). (D) The N-type VGCC blocker ω-CgTx (5 μM, n = 4) reduced MEPP frequency and did not prevent the modulatory effect of inosine on L-type VGCCs. Data (mean ± SEM) are expressed as percentage of control values. ***P < 0.001, ^##P < 0.01, anova followed by Tukey's test.