Calmodulin blockers inhibit endocytosis. (a) Top, sampled Cm induced by a 20-ms depolarization in the presence of scrambled CBD (CBD-c, 500 μM, left) or CBD (500 μM, right). Middle, mutated MLCK peptide (MLCK-c, 20 μM) or MLCK (20 μM). Bottom, 0.1% DMSO (control) or calmidazolium (Calm, 10 μM with 0.1% DMSO). (b) Data are presented as in a but with Cm induced by ten pulses of 20-ms depolarization at 10 Hz. (c) Sampled Cm induced by ten pulses of 50-ms depolarization at 10 Hz at a [Ca2+]o of 5.5 mM in control conditions (0.1% DMSO, left) or in the presence of 20 μM calmidazolium (with 0.1% DMSO, right). The arrow denotes the DCS from the left sampled trace on a different scale (middle). (d) The frequency of DCSs (right) induced by ten pulses of 50-ms depolarization at 10 Hz at a [Ca2+]o of 5.5 mM in control conditions (0.1% DMSO) or with 20 μM calmidazolium.