TABLE 1

Sensitivity to ATP of native and recombinant channels

Channel, conditionConfigurationIC50 (μmol/l)hn
Native, +Mg2+Open-cell156 ± 40*1.1 ± 0.210
Inside-out22 ± 21.5 ± 0.15
Native, Mg2+ freeOpen-cell15 ± 4.0 (NS)1.6 ± 0.210
Inside-out9.6 ± 0.81.0 ± 0.25
Kir6.2/SUR1, +Mg2+Open-cell371 ± 271.0 ± 0.16
Inside-out36 ± 8§0.9 ± 0.17
Kir6.2/SUR1, Mg2+ freeOpen-cell47 ± 3§1.1 ± 0.14
Kir6.2/SUR1-KAKM, +Mg2+Open-cell73 ± 140.9 ± 0.14
Inside-out31 ± 61.2 ± 0.27
Kir6.2/SUR1-KAKM, Mg2+ freeOpen-cell43 ± 10§1.1 ± 0.14
  • 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.