Cardiovascular Research Advance Access originally published online on March 13, 2008
Cardiovascular Research 2008 79(1):80-88; doi:10.1093/cvr/cvn069
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TWIK-related two-pore domain potassium channel TREK-1 in carotid endothelium of normotensive and hypertensive mice
1 Department of Internal Medicine-Nephrology, Philipps-University, Baldingerstrasse, 35033 Marburg, Hessen, Germany
2 Institute of Physiology and Pathophysiology, Philipps-University, Marburg, Germany
* Corresponding author. Tel: +49 6421 2866067; fax: +49 6421 2866116. E-mail address: rkoehler{at}med.uni-marburg.de
Aims: Potassium channels are essential elements of endothelial function. Recently, evidence emerged that the TWIK (tandem of P domains in a weak inwardly rectifying K+ channel)-related K+ channel (TREK-1) of the two-pore domain potassium channel gene family (K2P) may be involved in the regulation of vascular tone. However, the functional and molecular characterization of vascular TREK-1 is incomplete. In this study, we therefore analysed the functional expression of TREK-1 in the endothelium. Moreover, we hypothesized that changes in channel expression may contribute to altered endothelial vasodilator response under conditions of elevated blood pressure.
Methods: and results Gene expression and function of endothelial TREK-1 were analysed by single-cell RT–PCR, the patch-clamp technique and pressure myography in murine carotid arteries (CA). K+ outward currents displaying the characteristics of TREK-1 were observed following various TREK-1-activating stimuli such as membrane stretch, intracellular acidosis, polyunsaturated fatty acids, isoflurane (ISOFL), riluzole, and acetylcholine (ACh). In KCa3.1–/– mice exhibiting elevated blood pressure, endothelial TREK-1 currents and TREK-1 mRNA expression were enhanced as compared with normotensive control mice. TREK-1-mediated vasodilator responses to 
-linolenic acid, ISOFL, or ACh were increased. A similar up-regulation of endothelial TREK-1 was observed in spontaneously hypertensive rats.
Conclusion: We have found that TREK-1 is an endothelial K+ channel capable of producing hyperpolarization and vasodilation. A correlation between hypertension and up-regulation of TREK-1 was observed in two different animal models of elevated blood pressure. Thus, TREK-1 may play a protective role in the cardiovascular system by providing a novel type of endothelial hyperpolarization-mediated vasodilator response.
KEYWORDS Carotid artery; Endothelium-dependent vasodilation; Endothelium-derived hyperpolarizing factor; Hypertension; Mice; Two-pore domain potassium channel; KCa3.1; TREK-1; TREK-2; TRAAK
Time for primary review: 23 days
Contributed equally to this study.