title: [Expression and functional role of small conductance Ca(2+)-activated K(+) channels in human atrial myocytes].
abstract: OBJECTIVE
  To investigate the expression and functional role of the small conductance Ca(2+)-activated K(+) channels in human atrial myocytes.
  
  
  METHODS
  We collected the right atrial appendage tissues from 8 patients with congenital heart defect with sinus rhythm undergoing open-heart surgery. Immunohistochemistry was performed to identify the expression of 3 isoforms of SK channel (SK1, SK2 and SK3). Using the classical two-step enzymatic isolation method, perforated patch clamp and conventional voltage-clamp techniques were performed to record the action potentials (APs) and the whole-cell Ca(2+)-activated K(+) current (I(K, Ca)) in the single atrial myocyte. We compared the changes in action potential duration (APD) before and after the application of a specific SK channels blocker apamin (100 nmol/L).
  
  
  RESULTS
  Human atrial myocytes showed positivity for all the SK1, SK2 and SK3 isoform channels. Patch-clamp recording confirmed the presence of I(K,Ca), and apamin significantly prolonged APD at 90% repolarization (APD(90)), but produced no obvious effect on APD(50).
  
  
  CONCLUSIONS
  The three isoforms of SK channels are all expressed in human atrial myocytes. SK channels play a prominent role in the late phase of repolarization in human atrial myocytes, which is distinct from their functional roles in neurons where they mediate the process of afterhyperpolarization following APs.
authors.affiliation: Department of Cardiac Sugery, Guangdong Cardiovascular Institute, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou 510080, China. yutao7999@126.com
authors.forename: Tao
authors.initials: T
authors.lastname: YU
authors.forename: Ruo-bin
authors.initials: RB
authors.lastname: WU
authors.forename: Hui-ming
authors.initials: HM
authors.lastname: GUO
authors.forename: Chun-yu
authors.initials: CY
authors.lastname: DENG
authors.forename: Shao-yi
authors.initials: SY
authors.lastname: ZHENG
authors.forename: Su-juan
authors.initials: SJ
authors.lastname: KUANG
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000293:Adolescent; D020517:Atrial Appendage / Q000166:cytology; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D008297:Male; D032383:Myocytes, Cardiac / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D020033:Protein Isoforms / Q000378:metabolism / Q000502:physiology; D051640:Small-Conductance Calcium-Activated Potassium Channels / Q000378:metabolism* / Q000502:physiology*
chemical_list: D020033:Protein Isoforms; D051640:Small-Conductance Calcium-Activated Potassium Channels