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CYTOCHROME P450 2C‐DERIVED EPOXYEICOSATRIENOIC ACIDS REGULATE CA2+ SIGNALLING AND HYPERPOLARIZATION IN ENDOTHELIAL CELLS
Author(s) -
Rueben Alexandra,
Popp Rüdiger,
Keserü Benjamin,
Hammock Bruce D.,
Busse Rudi,
Fleming Ingrid
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a1288-b
Cytochrome P450 (CYP)‐derived epoxyeicosatrienoic acids (EETs) were proposed to act as Ca2+ influx factors in nonexcitable cells, largely on the basis of evidence obtained using non‐specific pharmacological tools. We set out to investigate the role of EETs generated by CYP 2C9 on Ca2+ signaling and the activation of Ca2+‐dependent K+ channels in human endothelial cells using a combination of overexpression techniques and inhibitors of the soluble epoxide hydrolase (sEH) which metabolizes EETs. In CYP‐deficient endothelial cells, bradykinin elicited a Ca2+ transient as well as membrane hyperpolarization. These responses were not affected by the CYP 2C9 inhibitor sulfaphenazole, or by the sEH inhibitor 1‐adamantyl‐3‐cyclohexylurea (ACU). In endothelial cells treated with nifedipine to induce CYP2C expression as well as in cells overexpressing CYP 2C9, ACU significantly enhanced the plateau phase of the bradykinin‐induced Ca2+ transient and prolonged the membrane hyperpolarization. Both effects were sensitive to sulfaphenazole as well as the EET antagonist 14,15‐epoxyeicosa‐5(Z)‐enoic acid and a protein kinase A (PKA) inhibitor. The transient receptor potential (TRP) channel blocker ruthenium red also prevented the ACU‐induced prolongation of endothelial cell hyperpolarization. These data indicate that CYP 2C9‐derived EETs regulate capacitative Ca2+ influx into endothelial cells via a PKA‐ and Trp‐dependent pathway and thereby modulate the agonist‐induced activation of Ca2+‐dependent K+ channels.