title: Swelling-activated and arachidonic acid-induced currents are TREK-1 in rat bladder smooth muscle cells.
abstract: Using the perforated patch voltage clamp, we investigated swelling-activated ionic channels (SACs) in rat urinary bladder smooth muscle cells.　Hypo-osmotic (60%) bath solution increased a membrane current which was inhibited by the SAC inhibitor, gadolinium.　The reversal potential of the hypotonicity-induced current shifted in the positive direction by increasing external K(+) concentration.　The hypotonicity-induced current was inhibited by extracellular acidic pH, phorbol ester and forskolin.　These pharmacological properties are identical to those of arachidonic acid-induced current present in these cells, suggesting the presence of TREK-1, a four-transmembrane two pore domain K(+) channel.　Using RT-PCR we screened rat bladder smooth muscles and cerebellum for expression of TREK-1, TREK-2 and TRAAK mRNAs.　Only TREK-1 mRNA was expressed in the bladder, while all three were expressed in the cerebellum.　We conclude that a mechanosensitive K(+) channel is present in rat bladder myocytes, which is activated by arachidonic acid and most likely is TREK-1.　This K(+) channel may have an important role in the regulation of bladder smooth muscle tone during urine storage.
authors.affiliation: Departments of Urolog, Fukushima Medical University.
authors.forename: Mitsuko
authors.initials: M
authors.lastname: Fukasaku
authors.forename: Junko
authors.initials: J
authors.lastname: Kimura
authors.forename: Osamu
authors.initials: O
authors.lastname: Yamaguchi
mesh_terms: D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology*; D005576:Colforsin / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects; D009130:Muscle, Smooth / Q000502:physiology*; D024683:Potassium Channels, Tandem Pore Domain / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D001743:Urinary Bladder / Q000502:physiology*
chemical_list: D024683:Potassium Channels, Tandem Pore Domain; C103742:potassium channel protein TREK-1; D005576:Colforsin; D016718:Arachidonic Acid; D013755:Tetradecanoylphorbol Acetate