Identification of 13-hydroxy-14,15-epoxyeicosatrienoic acid as an acid-stable endothelium-derived hyperpolarizing factor in rabbit arteries

J Biol Chem. 2009 Nov 6;284(45):31280-90. doi: 10.1074/jbc.M109.025627. Epub 2009 Sep 8.


Arachidonic acid (AA) is metabolized by endothelial 15-lipoxygenase (15-LO) to several vasodilatory eicosanoids such as 11,12,15-trihydroxyeicosatrienoic acid (11,12,15-THETA) and its proposed unstable precursor 15-hydroxy-11,12-epoxyeicosatrienoic acid (15-H-11,12-EETA). In the present study, the acid-stable 13-hydroxy-trans-14,15-epoxy-eicosatrienoic acid (13-H-14,15-EETA) was identified and its vascular activities characterized. Rabbit aorta, mesenteric arteries, and the combination of 15-LO and cytochrome P450 2J2 converted AA to two distinct HEETA metabolites. The HEETA metabolites were resistant to acidic hydrolysis but were hydrolyzed by recombinant sEH to a more polar metabolite identified by mass spectrometry as 13,14,15-THETA. Mass spectrometric analyses and HPLC comigration identified the HEETAs as threo- and erythro-diastereomers of 13-H-trans-14,15-EETA. Erythro- and threo-diastereomers of 13-H-trans-14,15-EETA relaxed endothelium-denuded rabbit small mesenteric arteries with maximum relaxations of 22.6 +/- 6.0% and 8.6 +/- 4.3%, respectively. Apamin (10(-7) m) inhibited the relaxations to the erythro-isomer (maximum relaxation = 1.2 +/- 5.6%) and increasing [K(+)](o) from 4.6 to 30 mm blocked relaxations to both isomers. In cell-attached patches of mesenteric arterial smooth muscle cells (SMCs), erythro-13-H-trans-14,15-EETA (1-3 x 10(-6) m) increased mean open time of small conductance K(+) channels (13-14 pS) from 0.0007 +/- 0.0007 to 0.0053 +/- 0.0042. This activation was inhibited by apamin. The erythro, but not the threo, isomer blocked angiotensin II-stimulated aortic SMC migration. These studies demonstrate that 13-H-14,15-EETAs induces vascular relaxation via K(+) channel activation to cause SMC hyperpolarization. Thus, 13-H-14,15-EETA represents a new endothelial factor.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 8,11,14-Eicosatrienoic Acid / analogs & derivatives*
  • 8,11,14-Eicosatrienoic Acid / chemistry
  • 8,11,14-Eicosatrienoic Acid / metabolism*
  • Acids / pharmacology
  • Animals
  • Arachidonic Acid / metabolism
  • Arteries / chemistry
  • Arteries / cytology
  • Arteries / drug effects
  • Arteries / metabolism*
  • Endothelium, Vascular / chemistry
  • Endothelium, Vascular / drug effects
  • Endothelium, Vascular / metabolism*
  • In Vitro Techniques
  • Rabbits
  • Vasodilator Agents / chemistry
  • Vasodilator Agents / metabolism*


  • Acids
  • Vasodilator Agents
  • Arachidonic Acid
  • 8,11,14-Eicosatrienoic Acid