Lloyd Eric E, Marrelli Sean P, Namiranian Khodadad, Bryan Robert M
Department of Anesthesiology, Room 434D, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
Exp Biol Med (Maywood). 2009 Dec;234(12):1493-502. doi: 10.3181/0903-RM-110.
TWIK-2, a member of the Two-Pore Domain K channel family, is expressed in a number of mammalian tissues including the vascular system. The function of TWIK-2 is not known. The purpose of this study was to clone the TWIK-2 channel from the rat middle cerebral artery, express it in CHO cells, and characterize the channel's electrical properties. In light of the fact that there are no specific TWIK-2 inhibitors or activators, a better characterization of the channel should enhance our understanding of its role in the vascular system. TWIK-2 was cloned from the rat middle cerebral artery and expressed with an N-terminal green fluorescence protein (GFP) in CHO cells. We report that rTWIK-2-GFP currents were relatively linear at physiological K(+) concentrations but become slightly inwardly rectifying in symmetrical K(+). rTWIK-2-GFP was insensitive to 10 mM TEA, 3 mM 4-aminopyridine, and 10 microM glibenclamide. However, rTWIK-2-GFP was inhibited by Ba(2+) with 50% of the current being blocked at 80 microM. rTWIK-2-GFP activity was enhanced 60% by 100 microM arachidonic acid. The electrophysiological characteristics of TWIK-2 indicate that it could serve an important role in ion homeostasis and regulation of the membrane potential in arteries and arterioles.
TWIK - 2是双孔域钾通道家族的成员之一，在包括血管系统在内的多种哺乳动物组织中表达。TWIK - 2的功能尚不清楚。本研究的目的是从大鼠大脑中动脉克隆TWIK - 2通道，在CHO细胞中表达，并表征该通道的电特性。鉴于目前尚无特异性的TWIK - 2抑制剂或激活剂，对该通道进行更好的表征应能增进我们对其在血管系统中作用的理解。从大鼠大脑中动脉克隆出TWIK - 2，并在CHO细胞中与N端绿色荧光蛋白（GFP）一起表达。我们报告，在生理钾离子浓度下，rTWIK - 2 - GFP电流相对呈线性，但在对称钾离子环境中会略微内向整流。rTWIK - 2 - GFP对10 mM四乙铵、3 mM 4 - 氨基吡啶和10 microM格列本脲不敏感。然而，rTWIK - 2 - GFP会被钡离子抑制，在80 microM时电流被阻断50%。100 microM花生四烯酸可使rTWIK - 2 - GFP活性增强60%。TWIK - 2的电生理特性表明，它可能在动脉和小动脉的离子稳态及膜电位调节中发挥重要作用。
