Activation of I_KACh by ACh is voltage-dependent.

a) Representative I_KACh recordings evoked at +30 mV (red traces) and -100 mV (black traces) by increasing concentrations of ACh. The dashed line symbolizes the zero current level. b) C-R curves for I_KACh activation by ACh at both voltages studied (red squares at +30 mV and black circles at -100 mV). Data were fitted to a Hill equation (solid lines). pEC₅₀ are mentioned in the text. Neither the maximum asymptote (1.01 ± 0.01 at +30 mV and 0.98 ± 0.01 at -100 mV) nor the Hill coefficient (1.04 ± 0.06 at +30 mV and 1.23 ± 0.07 at -100 mV) were significantly modified by voltage (P = 0.14 and 0.13, respectively; paired t test). n = 6 myocytes.