Krötz Florian, Riexinger Tobias, Buerkle Martin A, Nithipatikom Kasem, Gloe Torsten, Sohn Hae-Young, Campbell William B, Pohl Ulrich
Institute of Physiology, Medizinische Poliklinik-Innenstadt, Ludwig-Maximilians-University, München, Germany.
Arterioscler Thromb Vasc Biol. 2004 Mar;24(3):595-600. doi: 10.1161/01.ATV.0000116219.09040.8c. Epub 2004 Jan 8.
Epoxyeicosatrienoic acids (EETs) are potent vasodilators produced by endothelial cells. In many vessels, they are an endothelium-derived hyperpolarizing factor (EDHF). However, it is unknown whether they act as an EDHF on platelets and whether this has functional consequences.
Flow cytometric measurement of platelet membrane potential using the fluorescent dye DiBac4 showed a resting potential of -58+/-9 mV. Different EET regioisomers hyperpolarized platelets down to -69+/-2 mV, which was prevented by the non-specific potassium channel inhibitor charybdotoxin and by use of a blocker of calcium-activated potassium channels of large conductance (BK(Ca) channels), iberiotoxin. EETs inhibited platelet adhesion to endothelial cells under static and flow conditions. Exposure to EETs inhibited platelet P-selectin expression in response to ADP. Stable overexpression of cytochrome P450 2C9 in EA.hy926 cells (EA.hy2C9 cells) resulted in release of EETs and a factor that hyperpolarized platelets and inhibited their adhesion to endothelial cells. These effects were again inhibited by charybdotoxin and iberiotoxin.
EETs hyperpolarize platelets and inactivate them by inhibiting adhesion molecule expression and platelet adhesion to cultured endothelial cells in a membrane potential-dependent manner. They act as an EDHF on platelets and might be important mediators of the anti-adhesive properties of vascular endothelium.
环氧二十碳三烯酸（EETs）是内皮细胞产生的强效血管舒张剂。在许多血管中，它们是一种内皮源性超极化因子（EDHF）。然而，它们是否在血小板上作为EDHF起作用以及这是否具有功能后果尚不清楚。
使用荧光染料DiBac4通过流式细胞术测量血小板膜电位，显示静息电位为-58±9 mV。不同的EET区域异构体使血小板超极化至-69±2 mV，这被非特异性钾通道抑制剂蝎毒素以及使用大电导钙激活钾通道（BK（Ca）通道）阻滞剂iberiotoxin所阻止。EETs在静态和流动条件下均抑制血小板与内皮细胞的粘附。暴露于EETs可抑制血小板对ADP反应时P-选择素的表达。在EA.hy926细胞（EA.hy2C9细胞）中细胞色素P450 2C9的稳定过表达导致EETs和一种使血小板超极化并抑制其与内皮细胞粘附的因子的释放。这些作用再次被蝎毒素和iberiotoxin抑制。
EETs使血小板超极化并通过以膜电位依赖性方式抑制粘附分子表达和血小板与培养的内皮细胞的粘附而使其失活。它们在血小板上作为EDHF起作用，可能是血管内皮抗粘附特性的重要介质。
