Table 3.
Biophysical properties of cortical ISA and Kv4.2+KChIP3+DPP10a current expressed in oocytes
| Recording conditions and Voltage-dependence Parameters | ||||||
|---|---|---|---|---|---|---|
| Cell type | Temperature | E-junction | Activation | Inactivation | ||
|
|
||||||
| (°C) | (mV) | V0.5 (mV) |
slope factor (mV) |
V0.5 (mV) |
slope factor (mV) |
|
| Cortical pyramidal cell, Layer 2/3 | 21-23 | 4 | −4 | 12 | −51 | 7 |
| Cortical interneuron, Layer 2/3 | 20-22 | 2 | −15 | 18 | −77 | 11 |
| Cortical pyramidal cell, Layer 5 | 22-25 | 7 | −19 | 17 | −82 | 7 |
| Cortical pyramidal cell, Layer 5 | 20-22 | 2 | −5 | 20 | −68 | 10 |
| XO, Kv4.2 + KChIP3 + DPP10a | 21-23 | NA | −26 | 20 | −68 | 4 |
| XO, Kv4.2 + KChIP3 + DPP10c | 21-23 | NA | −20 | 18 | −62 | 5 |
| XO, Kv4.2 + KChIP3 + DPP10d | 21-23 | NA | −24 | 18 | −64 | 4 |
| Time to Peak and Kinetic Parameters | ||||
|---|---|---|---|---|
| Cell type | Inactivation at +30 mV (t0.5, ms) |
Inactivation Volt-dependence |
Recovery at −100 mV (τ, ms) |
Reference |
| Cortical pyramidal cell, Layer 2/3 |
|
NA | Zhou & Hablitz, 1996 | |
| Cortical interneuron, Layer 2/3 | 60 | Korngreen et al., 2005 | ||
| Cortical pyramidal cell, Layer 5 | 41 | Bekkers, 2000a | ||
| Cortical pyramidal cell, Layer 5 | 28 | Korngreen & Sakmann, 2000 | ||
| XO, Kv4.2 + KChIP3 + DPP10a | 28 | this study | ||
| XO, Kv4.2 + KChIP3 + DPP10c | 36 | U-shaped | 20 | this study |
| XO, Kv4.2 + KChIP3 + DPP10d | 38 | U-shaped | 24 | this study |
For comparison with published ISA data, only the mean values for experimental data are shown. Experimental data from this study were analyzed as described in Experimental Methods. All experiments were both conducted at approximately room temperature. When possible, V0.5 of activation and inactivation have been corrected for the indicated junction potentials (E-junction). The time constants (τ) of inactivation kinetics from published data have been converted to t0.5 by using the relationship: t0.5 = ln(2) * t. The voltage-dependence of inactivation is described as “monotonic” when the literature clearly states that inactivation time course at depolarized potential is “voltage independent” or “weakly voltage dependent”. Box outlines the critical similarity between Kv4.2+KChIP3+DPP10a current in oocytes when compared to cortical ISA. NA = not available. XO = Xenopus oocytes.