Sensitivity to ATP of native and recombinant channels
Channel, condition | Configuration | IC50 (μmol/l) | h | n |
---|---|---|---|---|
Native, +Mg2+ | Open-cell | 156 ± 40* | 1.1 ± 0.2 | 10 |
Inside-out | 22 ± 2 | 1.5 ± 0.1 | 5 | |
Native, Mg2+ free | Open-cell | 15 ± 4.0 (NS) | 1.6 ± 0.2 | 10 |
Inside-out | 9.6 ± 0.8 | 1.0 ± 0.2 | 5 | |
Kir6.2/SUR1, +Mg2+ | Open-cell | 371 ± 27† | 1.0 ± 0.1 | 6 |
Inside-out | 36 ± 8§ | 0.9 ± 0.1 | 7 | |
Kir6.2/SUR1, Mg2+ free | Open-cell | 47 ± 3§ | 1.1 ± 0.1 | 4 |
Kir6.2/SUR1-KAKM, +Mg2+ | Open-cell | 73 ± 14‡ | 0.9 ± 0.1 | 4 |
Inside-out | 31 ± 6 | 1.2 ± 0.2 | 7 | |
Kir6.2/SUR1-KAKM, Mg2+ free | Open-cell | 43 ± 10§ | 1.1 ± 0.1 | 4 |
Data are means ± SE. Results from native KATP channels (in β-cells) or recombinant KATP channels expressed in HEK cells (Kir6.2/SUR1; Kir6.2/SUR1-KAKM). Mg2+ was present in the internal solution as indicated.
* P < 0.005;
† P < 0.01;
‡ P < 0.05; NS, nonsignificant, when compared with equivalent data in the inside-out patch configuration.
§ Nonsignificant compared with open-cell data in Mg2+-containing solution for Kir6.2/SUR1-KAKM. h, Hill coefficient; n, number of patches.