rbE-II Ca channels are strongly stimulated through muscarinic receptors. Left, rbE-II current amplitudes are plotted as a function of time during representative experiments.Right, Whole-cell Ca currents recorded at times indicated in the corresponding plot. A, Stimulation of rbE-II current through M2 receptors (M2R). Ca currents were evoked every 3 sec by step depolarizations from −90 to +30 mV.C = 50 pF; R_S = 1.1 MΩ. The application of CCh (50 μm) is indicated by ahorizontal bar; this CCh concentration produces maximal activation of M2 receptors (Melliti et al., 1999; Meza et al., 1999).B, Stimulation of rbE-II current through M1 receptors (M1R). Ca currents were evoked every 5 sec by step depolarizations from −90 to +30 mV. C = 28 pF;R_S = 1.5 MΩ. The concentration of applied CCh was 1 mm. C, Average stimulation of rbE-II currents through M1 and M2 receptors.