Table 1.
Inhibition of inward rectifier currents in Xenopus oocytes by Ba2+
| Channel | IC50, μM | SEM | n |
|---|---|---|---|
| Homomeric channels | |||
| Kir2.1 | 3.2 | 0.36 | 5 |
| Kir2.2 | 0.5 | 0.04 | 5 |
| Kir2.3 | 10.3 | 0.61 | 5 |
| Concatemers | |||
| Kir2.1–Kir2.2 or Kir2.2–Kir2.1 | 0.68 | 0.04 | 10 |
| Kir2.1–Kir2.3 or Kir2.3–Kir2.1 | 3.39 | 0.48 | 7 |
| Kir2.2–Kir2.3 or Kir2.3–Kir2.2 | 1.73 | 0.29 | 6 |
| Coexpression | |||
| Kir2.1 + Kir2.2 | 0.64 | 0.05 | 5 |
| Kir2.1 + Kir2.3 | 6.32 | 0.29 | 5 |
| Kir2.2 + Kir2.3 | 1.94 | 0.18 | 5 |
The IC50 values were measured after expression of Kir2.x subunits or Kir2.x–Kir2.y concatemers, and after coexpression of different Kir2.x channel subunits. To calculate the IC50 the data were fitted with the function IBa/Icon = 1/(1 + [Ba2+]/IC50), where IBa and Icon are the currents measured in the presence and absence of Ba2+, respectively.