title: Molecular analysis of ATP-sensitive K⁺ channel subunits expressed in mouse vas deferens myocytes.
abstract: OBJECTIVE
  ATP-sensitive K(+)(K(ATP)) channels, which are composed of K(IR)6.x associated with sulphonylurea receptor (SUR) subunits, have been detected in native smooth muscle cells, but it is currently not known which of these is expressed in mouse vas deferens myocytes.
  
  
  METHODS
  Pharmacological and electrophysiological properties of K(ATP) channels in mouse vas deferens myocytes were investigated using patch clamp techniques. Molecular biological analyses were performed to examine the properties of these K(ATP) channels.
  
  
  RESULTS
  During conventional whole-cell recording, pinacidil elicited an inward current that was suppressed by glibenclamide, a sulfonylurea agent, and by U-37883A, a selective K(IR)6.1 blocker. When 0.3 mM ATP was added to the pipette solution, the peak amplitude of the pinacidil-induced current was much smaller than that recorded in its absence. When 3 mM UDP, GDP or ADP was included in the pipette solution, an inward current was elicited after establishment of the conventional whole-cell configuration, with potency order being UDP > GDP > ADP. These nucleoside diphosphate-induced inward currents were suppressed by glibenclamide. MCC-134, a SUR modulator, induced glibenclamide-sensitive K(ATP) currents that were similar to those induced by 100 μM pinacidil. In the cell-attached configuration, pinacidil activated channels with a conductance similar to that of K(IR)6.1. Reverse transcription PCR analysis revealed the expression of K(IR)6.1 and SUR2B transcripts and immunohistochemical studies indicated the presence of K(IR)6.1 and SUR2B proteins in the myocytes.
  
  
  CONCLUSIONS
  Our results indicate that native K(ATP) channels in mouse vas deferens myocytes are a heterocomplex of K(IR)6.1 channels and SUR2B subunits.
authors.affiliation: Department of Surgery and Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.
authors.forename: Kazuomi
authors.initials: K
authors.lastname: Iwasa
authors.forename: Hai-Lei
authors.initials: HL
authors.lastname: Zhu
authors.forename: Atsushi
authors.initials: A
authors.lastname: Shibata
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Maehara
authors.forename: Noriyoshi
authors.initials: N
authors.lastname: Teramoto
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D006153:Guanosine Diphosphate / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D054086:KATP Channels / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008564:Membrane Potentials; D051379:Mice; D008807:Mice, Inbred BALB C; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000378:metabolism*; D026902:Potassium Channel Blockers / Q000494:pharmacology; D064233:Sulfonylurea Receptors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D014530:Uridine Diphosphate / Q000378:metabolism; D014649:Vas Deferens / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*
chemical_list: C577511:Abcc9 protein, mouse; D054086:KATP Channels; D026902:Potassium Channel Blockers; D064233:Sulfonylurea Receptors; C092520:uK-ATP-1 potassium channel; D006153:Guanosine Diphosphate; D014530:Uridine Diphosphate; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate
keywords: KATP channels; KIR6.1; SUR2B; vas deferens myocytes