Table 1. Electrophysiological parameters of WT and mutants Kv7.1 channels.
| Kv7.1 construct | V50 (mV) | Iinst/Imax ratio | Rectification index | ||
| −Cd2+ | +Cd2+ | −Cd2+ | +Cd2+ | ||
| WT (12) | −24.1±2.3 | 0.11±0.03 | 0.10±001 | 0.035 | 0.022 |
| Q220C (20) | −18.7±0.8 | 0.13±0.01 | 0.12±0.01 | 0.139 | 0.132 |
| V221C (5) | −20.5±3.5 | 0.12±0.02 | 0.11±0.02 | 0.033 | 0.032 |
| F222C (17) | −8.3±1.3 ** | 0.13±0.02 | 0.11±0.01 | 0.146 | 0.200 |
| S225C (8) | −1.9±1.5 ** | 0.20±0.02 | 0.45±0.04 # | 0.139 | 0.066 |
| A226C (8) | −18.0±0.4 | 0.10±0.02 | 0.12±0.02 | 0.077 | 0.105 |
| I227C (11) | −13.6±1.7 ** | 0.10±0.01 | 0.99±0.01 ## | 0.064 | 0.481 ## |
| R228C (9) | +3.9±1.3 ** | 0.22±0.03 | 0.73±0.03 ## | 0.125 | 0.536 ## |
| S225C-C136A (10) | −8.2±2.3 ** | 0.18±002 | 0.21±0.02 | 0.045 | 0.046 |
| S225C-C214A (6) | −1.7±2.2 ** | 0.20±0.01 | 0.44±0.03 # | 0.120 | 0.218 |
| S225C-C331A (6) | −4.5±0.8 ** | 0.21±0.02 | 0.45±0.04 # | 0 | 0 |
| I227C-C136A (12) | −38.5±3.1 ** | 0.11±0.01 | 0.98±0.02 ## | 0.026 | 0.506 ## |
| I227C-C214A (12) | −34.2±3.9 ** | 0.12±0.02 | 0.88±0.03 ## | 0.071 | 0.722 ## |
| I227C-C331A (8) | −34.1±0.8 * | 0.10±0.02 | 0.90±0.03 ## | 0.014 | 0.254 ## |
| R228C-C136A (7) | +12.1±2.0 ** | 0.21±0.02 | 0.23±0.02 | 0.241 | 0.223 |
| R228C-C214A (7) | +14.0±2.0 ** | 0.23±0.02 | 0.71±0.04 ## | 0.218 | 0.624 ## |
| R228C-C331A (7) | +8.2±2.5 ** | 0.22±0.02 | 0.75±0.04 ## | 0.126 | 0.558 ## |
Activation curves were fit to a Boltzmann distribution, G/Gmax = 1/{1+exp[(V50-V)/s]}, where V50 is the voltage at which the current is half-activated and s is the slope factor. V50s were determined in the absence of Cd2+. Data are expressed as mean±SEM and in parentheses are indicated the number of cells.
, p<0.05
, p<0.01 vs. WT, (one way ANOVA followed by Dunnett's Multiple Comparison Test). To determine the Iinst/Imax ratio and the rectification index, oocytes were recorded in the absence (−Cd2+) or presence of 100 µM Cd2+ (+Cd2+). The Iinst/Imax ratio has been calculated by the ratio of the instantaneous current at the beginning of the pulse at +40 mV (Iinst) that follows the capacitive transient and the current at the end of the pulse at +40 mV (Imax). The larger is this ratio, the larger is the instantaneous open component.
, p<0.05,
, p<0.01 +Cd2+ versus −Cd2+ (two-tailed, Student's paired t test). The rectification index corresponds to the ratio of the current amplitude measured at −140 mV to that measured at −5 mV. The larger is this ratio, the stronger is the constitutive open leak K+ current component. Due to lack of space, are shown only the means (without SEMs) of the rectification index for the same number of tested cells indicated in parentheses.