Table 1.
Properties and modulation by insulin of Kv1.3 ion channel coexpressed with wild-type or truncated insulin receptor kinase
| Channel Construct and Treatment | Peak Current (pA) | Inactivation τ (ms) | Deactivation τ (ms) | Activation (V1/2) (mV) | Voltage Dependence (k) |
|---|---|---|---|---|---|
| Kv1.3 + IR kinase | |||||
| Control (n = 7) | 1124 ± 146 | 724 ± 83 | 41 ± 7 | −45.1 ± 1.4 | 3.1 ± 0.25 |
| Insulin (0.1 μg/ml) | 832 ± 148* | 608 ± 126 | 46 ± 6 | −46.5 ± 0.4 | 3.3 ± 0.21 |
| Kv1.3 + IR kinase | |||||
| Control (n = 7) | 931 ± 226 | 758 ± 70 | 16 ± 2 | −43.1 ± 1.3 | 3.2 ± 0.19 |
| Insulin (50 μg/ml) | 1033 ± 245 | 640 ± 74 | 25 ± 5* | −44.9 ± 1.5 | 3.2 ± 0.15 |
| Kv1.3 + IR(trunc) | |||||
| Control (n = 10) | 1304 ± 246 | 776 ± 39 | 18 ± 3 | −44.5 ± 1.6 | 3.3 ± 0.18 |
| Insulin (0.1 μg/ml) | 1170 ± 192 | 604 ± 58* | 17 ± 3 | −44.2 ± 1.6 | 3.6 ± 0.22 |
Currents were evoked by 1-s depolarizing pulses to +40 mV from rest (−80 mV), whereas HEK 293 cells were voltage-clamped in the cell-attached configuration. Values are means ± SE. Time constant (τ) values were estimated from exponential fits to the inactivating or deactivating portions of the current. The V1/2, the voltage at which half the channels were activated, was calculated by fitting normalized peak tail currents at different holding potentials to a Boltzmann function. The slope of this function or the value for steepness of the voltage dependence is reported as k.
Insulin-treated is significantly different from control by paired t-test.