Figure 2.

CCh-induced sADP requires intracellular Ca²⁺. (A) Applying BAPTA in the patch pipette solution decreased the sADP in presence of 10 μM CCh. Inset: Superimposed traces showing the sADP following action potentials induced by a depolarizing current step (bottom trace) in CCh under control conditions (black trace) or with 10 mM (gray trace) or 20 mM (red trace) BAPTA in the patch pipette solution. Initial V_m was −66 mV. Bar graph, number of action potentials during the depolarizing step (200 pA for 500 ms) was not significantly different among groups (n = 7–16, P = 0.31 and 1 respectively). (B) Bath application of Cd²⁺ reduced the sADP. Inset: sADPs induced by a depolarizing current step (in CCh) under control conditions (black trace) or in the presence of 100 μM Cd²⁺ (red trace). Bar graph, number of spikes during the depolarization was not affected by Cd²⁺ (n = 6–16, P = 0.77). (C) BAPTA significantly reduced peak amplitude (n = 6–14, * P < 0.05, *** P < 0.0001) and area (n = 6–14, *** P < 0.0001) of sADP triggered by a 200 pA depolarizing current step for 500 ms. (D) Cd²⁺ decreased sADP amplitude (n = 6–13, *** P < 0.001) and area (n = 6–14, ** P < 0.01).