This Article Full Text Full Text (PDF) Data Supplement All Versions of this Article: 27/12/2612    most recent ATVBAHA.107.152074v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Fleming, I. Articles by Busse, R. Search for Related Content PubMed PubMed Citation Articles by Fleming, I. Articles by Busse, R. Related Collections Related Article

(Arteriosclerosis, Thrombosis, and Vascular Biology. 2007;27:2612.)
© 2007 American Heart Association, Inc.

Vascular Biology

Epoxyeicosatrienoic Acids Regulate Trp Channel–Dependent Ca²⁺ Signaling and Hyperpolarization in Endothelial Cells

Ingrid Fleming; Alexandra Rueben; Rüdiger Popp; Beate Fisslthaler; Susanne Schrodt; Anna Sander; Judith Haendeler; John R. Falck; Christophe Morisseau; Bruce D. Hammock; Rudi Busse

From the Vascular Signaling Group, Institut für Kardiovaskuläre Physiologie (I.F., A.R., R.P., B.F., S.S., A.S., R.B.), and Molecular Cardiology (J.H.), Department of Internal Medicine III, Johann Wolfgang Goethe-Universität, Frankfurt am Main, Germany; the Department of Biochemistry (J.R.F.), University of Texas Southwestern Medical Center, Dallas; and the Department of Entomology (C.M., B.D.H.), University of California, Davis.

Correspondence to Ingrid Fleming, PhD, Vascular Signalling Group, Institut für Kardiovaskuläre Physiologie, Johann Wolfgang Goethe-Universität, Theodor-Stern-Kai 7, D-60590 Frankfurt am Main, Germany. E-mail fleming{at}em.uni-frankfurt.de

Objective— An initial step in endothelium-derived hyperpolarizing factor-mediated responses is endothelial cell hyperpolarization. Here we address the mechanisms by which cytochrome P450 (CYP)-derived epoxyeicosatrienoic acids (EETs) contribute to this effect in native and cultured endothelial cells.

Methods and Results— In native CYP2C-expressing endothelial cells, bradykinin elicited a Ca²⁺ influx that was potentiated by the soluble epoxide hydrolase inhibitor, 1-adamantyl-3-cyclohexylurea (ACU), and attenuated by CYP inhibition. Similar effects were observed in cultured endothelial cells overexpressing CYP2C9, but not in CYP2C9-deficient cells, and were prevented by the EET antagonist 14,15-epoxyeicosa-5(Z)-enoic acid as well as by the cAMP antagonist, Rp-cAMPS. The effects on Ca²⁺ were mirrored by prolongation of the bradykinin-induced hyperpolarization. Ruthenium red and the combination of charybdotoxin and apamin prevented the latter effect, suggesting that Trp channel activation increases Ca²⁺ influx and prolongs the activation of Ca²⁺-dependent K⁺ (K_Ca) channels. Indeed, overexpression of CYP2C9 enhanced the agonist-induced translocation of a TrpC6-V5 fusion protein to caveolin-1–rich areas of the endothelial cell membrane, which was prevented by Rp-cAMPS and mimicked by 11,12-EET.

Conclusions— Elevated EET levels regulate Ca²⁺ influx into endothelial cells and the subsequent activation of K_Ca channels, via a cAMP/PKA-dependent mechanism that involves the intracellular translocation of Trp channels.

Bradykinin-induced Ca²⁺ influx and Ca²⁺-dependent K⁺ channel activation in endothelial cells is potentiated by cytochrome P450 (CYP) expression and soluble epoxide hydrolase (sEH) inhibition. An epoxyeicosatrienoic acid-induced translocation of a TrpC6-V5 fusion protein to the endothelial cell membrane via a cAMP-dependent mechanism can account for these findings.

Key Words: caveolae • cytochrome P450 • endothelium-derived hyperpolarizing factor • protein kinase A

Related Article:

Epoxyeicosatrienoic Acids, TRP Channels, and Intracellular Ca²⁺ in the Vasculature: An Endothelium-Derived Endothelium-Hyperpolarizing Factor?

Brandon T. Larsen, David X. Zhang, and David D. Gutterman
Arterioscler. Thromb. Vasc. Biol. 2007 27: 2496-2498. [Full Text] [PDF]

This article has been cited by other articles:

				J.-K. Chen, J. Chen, J. D. Imig, S. Wei, D. L. Hachey, J. S. Guthi, J. R. Falck, J. H. Capdevila, and R. C. Harris Identification of Novel Endogenous Cytochrome P450 Arachidonate Metabolites with High Affinity for Cannabinoid Receptors J. Biol. Chem., September 5, 2008; 283(36): 24514 - 24524. [Abstract] [Full Text] [PDF]

				A. E. Loot, R. Popp, B. Fisslthaler, J. Vriens, B. Nilius, and I. Fleming Role of cytochrome P450-dependent transient receptor potential V4 activation in flow-induced vasodilatation Cardiovasc Res, August 27, 2008; (2008) cvn207v2. [Abstract] [Full Text] [PDF]

				J. Saliez, C. Bouzin, G. Rath, P. Ghisdal, F. Desjardins, R. Rezzani, L.F. Rodella, J. Vriens, B. Nilius, O. Feron, et al. Role of Caveolar Compartmentation in Endothelium-Derived Hyperpolarizing Factor-Mediated Relaxation: Ca2+ Signals and Gap Junction Function Are Regulated by Caveolin in Endothelial Cells Circulation, February 26, 2008; 117(8): 1065 - 1074. [Abstract] [Full Text] [PDF]