# Effects of membrane potential on *I*_{KACh} evoked by Ado through A_{1}R in guinea pig atrial myocytes.

**a**) Examples of *I*_{KACh} traces elicited when sequentially perfusing the cells with increasing Ado concentrations and recorded at V_{h} of +30 mV (red traces) and -100 mV (black traces). The zero current level is indicated by the dashed line. **b**) C-R relationships for *I*_{KACh} activated by Ado at V_{h} +30 mV (red circles) and -100 mV (black squares). The filled symbols represent the current amplitudes normalized to that activated by 100 μM Ado. The solid lines depict the best data fit to a Hill equation. The pEC_{50} values are reported in the text. The maximum asymptote (0.98 ± 0.01 at +30 mV and 1.00 ± 0.01 at -100 mV) was not significantly altered by voltage (P = 0.16; Wilcoxon signed rank test) neither was the Hill coefficient (1.03 ± 0.12 at +30 mV and 1.02 ± 0.09 at -100 mV) (*P* = 0.98; paired *t* test). *n* = 9 myocytes. For this and subsequent figures, the filled symbols represent the mean values, while the open symbols denote the individual raw data points.