Epoxyeicosatrienoic Acid Relaxing Effects Involve Ca2+-Activated K+ Channel Activation and CPI-17 Dephosphorylation in Human Bronchi
| Autor: | Marcio M. Gomes, Marco Sirois, Caroline Morin, Vincent Echave, Eric Rousseau |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
Pulmonary and Respiratory Medicine
Myofilament Muscle Relaxation Myocytes Smooth Muscle Clinical Biochemistry Muscle Proteins Bronchi In Vitro Techniques Epoxyeicosatrienoic acid Membrane Potentials Dephosphorylation Potassium Channels Calcium-Activated chemistry.chemical_compound 8 11 14-Eicosatrienoic Acid Phorbol Esters Phosphoprotein Phosphatases medicine Humans Phosphorylation Molecular Biology Membrane potential Intracellular Signaling Peptides and Proteins Antagonist Cell Biology Amides chemistry Eicosanoid Biochemistry Muscle Tonus Potassium cardiovascular system Biophysics Calcium lipids (amino acids peptides and proteins) Arachidonic acid Methacholine Ion Channel Gating medicine.drug |
| Zdroj: | American Journal of Respiratory Cell and Molecular Biology. 36:633-641 |
| ISSN: | 1535-4989 1044-1549 |
| DOI: | 10.1165/rcmb.2006-0281oc |
| Popis: | The aim of the present study was to provide a mechanistic insight into how 14,15-epoxyeicosatrienoic acid (EET) relaxes organ-cultured human bronchi. Tension measurements, performed on either fresh or 3-d-cultured bronchi, revealed that the contractile responses to 1 microM methacholine and 10 microM arachidonic acid were largely relaxed by the eicosanoid regioisomer in a concentration-dependent manner (0.01-10 microM). Pretreatments with 14,15-epoxyeicosa-5(Z)-enoic acid, a specific 14,15-EET antagonist, prevented the relaxing effect, whereas iberitoxin pretreatments (10 nM) partially abolished EET-induced relaxations. In contrast, pretreatments with 1 microM indomethacin amplified relaxations in explants and membrane hyperpolarizations triggered by 14,15-EET on airway smooth muscle cells. The relaxing responses induced by 14,15-EET were likely related to reduced Ca2+ sensitivity of the myofilaments, because free Ca2+ concentration-response curves performed on beta-escin-permeabilized cultured explants were shifted toward higher [Ca2+] (lower pCa2+ values). 14,15-EET also abolished the tonic responses induced by phorbol-ester-dybutyrate (PDBu) (a protein kinase C [PKC]-sensitizing agent), on both fresh (intact) and beta-escin-permeabilized explants. Western blot analyses, using two specific primary antibodies against CPI-17 and its PKC-dependent phosphorylated isoform (p-CPI-17), confirmed that the eicosanoid interferes with this intracellular process. These data indicate that 14,15-EET hyperpolarizes airway smooth muscle cells and relaxes precontracted human bronchi while reducing Ca2+ sensitivity of fresh and cultured explants. The intracellular effects are related to a PKC-dependent process involving a lower phosphorylation level of CPI-17. |
| Databáze: | OpenAIRE |
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