Eicosapentaenoic acid (EPA) induces Ca²⁺‐independent activation and translocation of endothelial nitric oxide synthase and endothelium‐dependent vasorelaxation

Abstract

Eicosapentaenoic acid (EPA), but not its metabolites (docosapentaenoic acid and docosahexaenoic acid), stimulated nitric oxide (NO) production in endothelial cells in situ and induced endothelium-dependent relaxation of bovine coronary arteries precontracted with U46619. EPA induced a greater production of NO, but a much smaller and more transient elevation of intracellular Ca 2+ concentration ([Ca 2+ ]i), than did a Ca 2+ ionophore (ionomycin). EPA stimulated NO production even in endothelial cells in situ loaded with a cytosolic Ca 2+ chelator 1,2-bis-o-aminophenoxythamine-NP P,NP P,NP P-tetraacetic acid, which abolished the [Ca 2+ ]i elevations induced by ATP and EPA. The EPA-induced vasorelaxation was inhibited by N gnitro-L-arginine methyl ester. Immunostaining analysis of endothelial NO synthase (eNOS) and caveolin-1 in cultured endothelial cells revealed eNOS to be colocalized with caveolin in the cell membrane at a resting state, while EPA stimulated the translocation of eNOS to the cytosol and its dissociation from caveolin, to an extent comparable to that of the eNOS translocation induced by a [Ca 2+ ]i-elevating agonist (10 W WM bradykinin). Thus, EPA induces Ca 2+ -independent activation and translocation of eNOS and endothelium-dependent vasorelaxation. ß 2001 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.

Sphingomyelinase causes endothelium‐dependent vasorelaxation through endothelial nitric oxide production without cytosolic Ca2+ elevation

“…This process has been considered to be a major mechanism for the Ca 2+ -dependent activation of eNOS in endothelial cells [18]. However, we previously reported that eicosapentaenoic acid induces Ca 2+ -independent activation of eNOS in endothelial cells, which is accompanied with the translocation of membrane eNOS to the cytosol [7]. In addition, Igarashi et al previously demonstrated that C 2 -ceramide, a membrane permeable ceramide, stimulates NO production without [Ca 2+ ] i elevation in cultured endothelial cells, which is accompanied with the translocation of eNOS from caveolin-bound caveolae [19].…”

“…Confocal images of immunocytochemistry of strips of bovine aortic valves (2 · 3 mm) were observed under a confocal laser scan microscope (LSM510, Zeiss), as described [7]. The fixed and permeabilized cells were incubated with monoclonal mouse anti-eNOS (Transduction Laboratories) and rabbit anti-caveolin-1 (Santa Cruz Biotechnology) antibodies, then incubated with an Alexa546-conjugated anti-mouse IgG (Molecular Probe) and an Alexa488-conjugated anti-rabbit IgG (Molecular Probe).…”

Improvement of Major Depression is Associated with Increased Erythrocyte DHA

“…While DHA is an essential fatty acid component of brain tissue required for neurotransmission, EPA may possibly influence central nervous system activity by influencing cerebral blood flow through endothelial vasodilator mechanisms [24]. DHA is incorporated into phosphatidylethanolamine and phosphatidyl-serine in the gray matter of the brain [25] and phosphatidylserine-DHA has been linked to neuronal cell survival [26,27].…”

Effects of Docosahexaenoic Acid on the Endothelial Function in Patients with Coronary Artery Disease

“…It has also been reported that n-3 PUFA increases the expression and activation of eNOS, leading to vasodilation 17) . Furthermore, the EPA-induced translocation of eNOS from caveolin in the cell membrane to the cytosol results in the enhancement and activation of the eNOS system and may a cause of EPA-induced vasodilation 18) . Meanwhile, DHA has been reported to decrease the expression of proinflammatory cytokines (e.g.…”