Temperature-sensitive TREK currents contribute to setting the resting membrane potential in embryonic atrial myocytes.

Published

Journal Article

TREK channels belong to the superfamily of two-pore-domain K(+) channels and are activated by membrane stretch, arachidonic acid, volatile anaesthetics and heat. TREK-1 is highly expressed in the atrium of the adult heart. In this study, we investigated the role of TREK-1 and TREK-2 channels in regulating the resting membrane potential (RMP) of isolated chicken embryonic cardiac myocytes. At room temperature, the average RMP of embryonic day (ED) 11 atrial myocytes was -22 +/- 2 mV. Raising the temperature to 35 degrees C hyperpolarized the membrane to -69 +/- 2 mV and activated a large outwardly rectifying K(+) current that was relatively insensitive to conventional K(+) channel inhibitors (TEA, 4-AP and Ba(2+)) but completely inhibited by tetracaine (200 microM), an inhibitor of TREK channels. The heat-induced hyperpolarization was mimicked by 10 microM arachidonic acid, an agonist of TREK channels. There was little or no inwardly rectifying K(+) current (I(K1)) in the ED11 atrial cells. In marked contrast, ED11 ventricular myocytes exhibited a normal RMP (-86.1 +/- 3.4 mV) and substantial I(K1), but no temperature- or tetracaine-sensitive K(+) currents. Both RT-PCR and real-time PCR further demonstrated that TREK-1 and TREK-2 are highly and almost equally expressed in ED11 atrium but much less expressed in ED11 ventricle. In addition, immunofluorescence demonstrated TREK-1 protein in the membrane of atrial myocytes. These data indicate the presence and function of TREK-1 and TREK-2 in the embryonic atrium. Moreover, we demonstrate that TREK-like currents have an essential role in determining membrane potential in embryonic atrial myocytes, where I(K1) is absent.

Full Text

Cited Authors

  • Zhang, H; Shepherd, N; Creazzo, TL

Published Date

  • August 2008

Published In

Volume / Issue

  • 586 / 15

Start / End Page

  • 3645 - 3656

PubMed ID

  • 18566002

Pubmed Central ID

  • 18566002

Electronic International Standard Serial Number (EISSN)

  • 1469-7793

International Standard Serial Number (ISSN)

  • 0022-3751

Digital Object Identifier (DOI)

  • 10.1113/jphysiol.2008.153395

Language

  • eng