Characterization of TWIK-2, a two-pore domain K+ channel, cloned from the rat middle cerebral artery.
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.
Lloyd
Eric E
EE
Department of Anesthesiology, Room 434D, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
Marrelli
Sean P
SP
Namiranian
Khodadad
K
Bryan
Robert M
RM
D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology; D001464:Barium / Q000494:pharmacology; D016466:CHO Cells; D003001:Cloning, Molecular; D006224:Cricetinae; D003412:Cricetulus; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology*; D020768:Middle Cerebral Artery / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism; D024683:Potassium Channels, Tandem Pore Domain / Q000096:biosynthesis* / Q000235:genetics; D051381:Rats; D020318:Rats, Long-Evans
C539081:Kcnk6 protein, rat; D024683:Potassium Channels, Tandem Pore Domain; D001464:Barium; D016718:Arachidonic Acid; D011188:Potassium