A swelling-activated, background K(+) current in the corneal epithelium is characteristically activated by fenamates and inhibited by diltiazem. Fatty acids also stimulate this current, indicating that its origin is a lipid-sensitive mechano-gated 2P domain K(+) channel. In the present study, modulation of TREK-1, TREK-2, and TRAAK channels by fenamates and diltiazem was examined. TREK-1, TREK-2, and TRAAK currents transiently expressed in COS-7 cells were recorded by the perforated-patch configuration. As previously reported, arachidonic acid (20 microM) stimulated all of these channels, and a volatile anesthetic, halothane (1 mM) augmented TREK-1 and TREK-2 but not TRAAK. Flufenamic acid (FA, 100 microM), niflumic acid (NA, 100 microM), and mefenamic acid (MA, 100 microM) markedly stimulated TREK-1, TREK-2, and TRAAK. The potency sequence for the activation of TREK-1 and TREK-2 was FA > NA = MA, and the potency sequence for the activation of TRAAK was FA = NA > MA. Diltiazem (1 mM) inhibited TREK-1 and TREK-2, but not TRAAK. In conclusion, fenamates are openers of the lipid-sensitive mechano-gated 2P domain K(+) channels, and diltiazem may be a specific blocker for TREK. These novel findings could help to further understand channel functions of the mechano-gated 2P domain K(+) channels.
Porcine PCE cells express a swelling-activated K(+) channel, which may be a member of the KCNQ/Kv7 channel family. This K(+) channel is active near resting potentials and could contribute to the regulation of cell volume and water transport via the ciliary epithelia.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.