Table 1.
Ito current characteristics in CHO expression systems with coexpression of KChIP2a and DPPX, 22°C
| Kv4.3 + KChIP2aa | n | Kv4.3 + DPPXb | n | Kv4.3 + KChIP2a + DPPXc | n | Humanventricularmyocytesd | n | |
|---|---|---|---|---|---|---|---|---|
| Cm (pF) | 33 ± 3 | 40 | 12 ± 2 | 8 | 39 ± 6 | 18 | 292 ± 22 | 28 |
| Im current density at +50 mV (pA pF−1) | 495 ± 86 | 26 | 399 ± 90 | 6 | 373 ± 50 | 15 | 7.9 ± 0.7 | 28 |
| τfast of inactivation at +50 mV (ms) | 55 ± 4 | 11 | 25 ± 6* | 8 | 45 ± 6 | 10 | 54 ± 3 | 5 |
| (58 ± 3) | (28) | |||||||
| τslow of inactivation at +50 mV (ms) | 392 ± 160 | 10 | 177 ± 16 | 8 | 427 ± 213 | 10 | n.d. | — |
| V0.5 of steady-stateinactivation (mV) | −31.3 ± 2.4 | 24 | −57.0 ± 3.1* | 8 | −39.8 ± 2.8 | 9 | −45.5 ± 1.2 | 5 |
| (−30.4 ± 1.2) | (26) | |||||||
| Slope k of steady-state inactivation (mV) | −5.0 ± 0.5 | 24 | −5.5 ± 0.4 | 8 | −6.6 ± 0.6 | 9 | −4.6 ± 0.8 | 5 |
| (−4.5 ± 0.2) | (26) | |||||||
| τfast of recovery from inactivation at+50 mV, from −80 mV (ms) | 42 ± 8 | 11 | 52 ± 16 | 8 | 18 ± 3* | 11 | 24 ± 3 | 6 |
| at +20 mV,from −100 mV |
*
Values significantly different from other groups P < 0.05.
a
Stable expression of Kv4.3 and KChiP2a.
b
Stable expression of Kv4.3 and transient expression of DPPX.
c
Stable expression of Kv4.3 and KChiP2a and transient expression of DPPX.
d
Data from Wettwer et al. (1994) for comparison, not included in statistical analysis; subepicardial myocytes, nifedipine (1 μm) or Cd2+ (0.1 mm, data in brackets) was used for block of ICa. n.d. values not determined.