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ATP-sensitive K(+) channels (K(ATP) channels) couple cell metabolism to electrical activity and thereby to physiological processes such as hormone secretion, muscle contraction, and neuronal activity. However, the mechanism by which metabolism regulates K(ATP) channel activity, and the channel sensitivity to inhibition by ATP in its native environment, remain controversial. Here, we used alpha-toxin to permeabilize single pancreatic beta-cells and measure K(ATP) channel ATP sensitivity. We show that the channel ATP sensitivity is approximately sevenfold lower in the permeabilized cell than in the inside-out patch and that this is caused by interaction of Mg-nucleotides with the nucleotide-binding domains of the SUR1 subunit of the channel. The ATP sensitivity observed in permeabilized cells accounts quantitatively for K(ATP) channel activity in intact cells. Thus, our results show that the principal metabolic regulators of K(ATP) channel activity are MgATP and MgADP.

Original publication




Journal article



Publication Date





2446 - 2454


ATP-Binding Cassette Transporters, Acyl Coenzyme A, Adenosine Diphosphate, Adenosine Triphosphate, Animals, Bacterial Toxins, Cell Membrane Permeability, Glucose, Hemolysin Proteins, Insulin-Secreting Cells, Mice, Patch-Clamp Techniques, Phosphatidylinositol 4,5-Diphosphate, Potassium Channels, Potassium Channels, Inwardly Rectifying, Receptors, Drug, Sulfonylurea Receptors