Inhibitory effects of epoxyeicosatrienoic acids on volume-activated chloride channels in rat mesenteric arterial smooth muscle

Prostaglandins Other Lipid Mediat. 2008 Dec;87(1-4):62-7. doi: 10.1016/j.prostaglandins.2008.08.003. Epub 2008 Sep 2.

Abstract

Epoxyeicosatrienoic acids (EETs) are synthesized from arachidonic acid by cytochrome P450 epoxygenases in endothelial cells. It has previously been shown that EETs activate K(+) channels, which are important for the hyperpolarization and dilation of blood vessels. However, the effects of EETs on other ion channels have been less well studied. We investigated the effects of EETs on volume-activated Cl(-) channels (VACCs) in rat mesenteric arterial smooth muscle cells. Whole-cell patch clamp recording demonstrated that hypotonic solution and guanosine 5'-[gamma-thio]triphosphate (GTPgammaS) induced a 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB)- and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS)-sensitive VACC current in the primary cultured rat mesenteric arterial smooth muscle cells. The VACC current was inhibited by EETs and the order of potency was 8,9-EET>5,6-EET>11,12-EET>14,15-EET. The inhibitory effects of EETs could be reversed by 14,15 epoxyeicosa-5(Z)-enoic acid (14,15-EEZE, an EET analog), Rp-cGMP and KT-5823 (protein kinase G inhibitors). Interestingly, the inhibitory effects of EETs on VACCs were not influenced by Rp-cAMP (a protein kinase A antagonist) but it could be abolished by NF-449 (a Gs protein inhibitor), indicating the involvement of cAMP but not protein kinase A. In conclusion, our results demonstrate that EETs inhibit VACCs in rat mesenteric arterial smooth muscle cells through a cGMP-dependent pathway, which is probably due to the cross-activation by cAMP. This mechanism may be involved in the regulation of cell volume and membrane potential.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 8,11,14-Eicosatrienoic Acid / pharmacology*
  • Animals
  • Chloride Channels / metabolism*
  • Male
  • Mesenteric Arteries / cytology*
  • Mesenteric Arteries / drug effects
  • Mesenteric Arteries / metabolism
  • Myocytes, Smooth Muscle / drug effects*
  • Myocytes, Smooth Muscle / metabolism*
  • Rats
  • Rats, Sprague-Dawley

Substances

  • Chloride Channels
  • 8,11,14-Eicosatrienoic Acid