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Garg P, Sanguinetti MC. Intracellular ATP does not inhibit Slo2.1 K+ channels. Physiol Rep. 2014;2(9)doi: 10.14814/phy2.12118.
Garg, P., & Sanguinetti, M. C. (2014). Intracellular ATP does not inhibit Slo2.1 K+ channels. Physiological reports, 2(9), . https://doi.org/10.14814/phy2.12118
Garg, Priyanka, and Sanguinetti, Michael C. "Intracellular ATP does not inhibit Slo2.1 K+ channels." Physiological reports vol. 2,9 (2014). doi: https://doi.org/10.14814/phy2.12118
Garg P, Sanguinetti MC. Intracellular ATP does not inhibit Slo2.1 K+ channels. Physiol Rep. 2014 Sep 11;2(9). doi: 10.14814/phy2.12118. Print 2014 Sep 01. PMID: 25214519; PMCID: PMC4270230.
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Physiol Rep. 2014 Sep 11;2(9). doi: 10.14814/phy2.12118. Print 2014 Sep 01.

Intracellular ATP does not inhibit Slo2.1 K+ channels.

Physiological reports

Priyanka Garg, Michael C Sanguinetti

Affiliations

  1. Nora Eccles Harrison Cardiovascular Research & Training Institute, University of Utah, Salt Lake City, Utah, USA Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, Salt Lake City, Utah, USA.
  2. Nora Eccles Harrison Cardiovascular Research & Training Institute, University of Utah, Salt Lake City, Utah, USA Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, Salt Lake City, Utah, USA Department of Internal Medicine, Division of Cardiovascular Medicine, University of Utah, Salt Lake City, Utah, USA.

PMID: 25214519 PMCID: PMC4270230 DOI: 10.14814/phy2.12118

Abstract

Under normal physiological conditions, the open probability of Slo2.1 K(+) channels is low. Elevation of cytosolic [Na(+)] and [Cl(-)] caused by ischemia or rapid electrical pacing of cells increases the open probability of Slo2.1 channels and the resulting outward current can stabilize the resting state of cells. Initial characterization of heterologously expressed human Slo2.1 indicated that these channels were inhibited by physiological levels of intracellular ATP. However, a subsequent study found that intracellular ATP had no effect on Slo2.1 channels. Here, we re-examine the effects of intracellular ATP on cloned human Slo2.1 channels heterologously expressed in Xenopus oocytes. Our studies provide both direct and indirect evidence that changes in intracellular [ATP] have no effect on Slo2.1 channels. First, we directly examined the effects of intracellular ATP on Slo2.1 channel activity in excised inside-out macropatches from Xenopus oocytes. Application of 5 mmol/L ATP to the intracellular solution did not inhibit Slo2.1 currents activated by niflumic acid. Second, we lowered the [ATP]i in whole oocytes using the metabolic inhibitor NaN3. Depletion of [ATP]i in oocytes by 3 mmol/L NaN3 rapidly activated heterologously expressed KATP channels, but did not increase wild-type Slo2.1 channel currents activated by niflumic acid or currents conducted by constitutively active mutant (E275D) Slo2.1 channels. Third, mutation of a conserved residue in the ATP binding consensus site in the C-terminal domain of the channel did not enhance the magnitude of Slo2.1 current as expected if binding to this site inhibited channel function. We conclude that Slo2.1 channels are not inhibited by intracellular ATP.

© 2014 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of the American Physiological Society and The Physiological Society.

Keywords: ATP; KCNT2; Xenopus; oocytes; potassium channels

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