Modulation of α1E Ca currents through M1 receptors. Inhibition and stimulation are expressed relative to the control Ca current in each cell, recorded immediately before CCh application. Each cell was exposed once to a single concentration of CCh. Means were compared using one-way ANOVA or by an unpaired, two-tailed t test. Asterisks indicate significant differences from the control mean (*p< 0.05; **p < 0.01; ***p < 0.001). The average Ca current densities (measured in response to a test pulse to +30 mV) in each group were 106 ± 17 pA/pF (n = 17) in control, 104 ± 23 pA/pF (n = 10) in PTX-treated, 80 ± 21 pA/pF (n = 10) in PLCβ1ct-expressing, 196 ± 88 pA/pF (n = 9) in RGS2-expressing, 68 ± 10 pA/pF (n = 8) in βARK1ct-expressing, 124 ± 19 pA/pF (n = 18) in RGS8-expressing, and 149 ± 38 pA/pF (n = 7) in ΔRGS8-expressing cells.