title: Existence of ATP sensitive potassium currents on human periodontal ligament cells.
abstract: OBJECTIVE
  Potassium channels of the ATP-sensitive family (KATPchannel) are inhibited by increase in intracellular ATP. Electrophysiological studies have demonstrated that the kinetics and pharmacological properties of KATPchannels vary among different tissues, suggesting structurally and functionally distinct types. There are studies showing human periodontal ligament (PDL) cells respond to mechanical stress by increasing ATP release, which participates in bone resorption or bone homeostasis. So, in this study we investigated the existence of KATPchannel subunit and their single channel properties in human periodontal ligaments.
  
  
  METHODS
  The human PDL cells were isolated from healthy erupted third molar. For patch-clamp experiments, human PDL fibroblasts were seeded on 3.5cm plastic dishes. The inside-out patch clamp recordings were performed under voltage clamp mode. Reverse transcriptase polymerase chain reaction (RT-PCR) was conducted to identify the channel subunits. All pair-wise comparisons were performed by Paired t-test. A P value <0.05 was considered significant.
  
  
  RESULTS
  We observed mRNA transcripts for Kir6.1, Kir6.2 and Sur2B subuits in the human PDL cells. In inside-out patch mode, the single channel conductance was 163pS at symmetrical K+concentration of 140mM and inward rectification was seen in ATP-free bath solution. The reversal potential of the currents was found to be 0mV at symmetrical concentration (140mM) of K+in bath solution. The single channel currents were almost blocked by adding 5mM ATP in the bath solution. However, the currents were not blocked by 100μM glibenclamide, a subunit specific KATPchannel blocker.
  
  
  CONCLUSIONS
  These results indicate that human PDL cells express KATPchannels subunit including Sur2B and Kir6.1 and Kir6.2 which are sensitive to ATP but insensitive to glibenclamide.
authors.affiliation: Department of Oral Physiology, School of Dentistry & Institute of Oral Bioscience, Chonbuk National University, Jeonju, South Korea.
authors.forename: Phuong Thi Huyen
authors.initials: PT
authors.lastname: Tran
authors.affiliation: Department of Oral Biochemistry, School of Dentistry & Institute of Oral Bioscience, Chonbuk National University, Jeonju, South Korea.
authors.forename: Young Hee
authors.initials: YH
authors.lastname: Lee
authors.affiliation: Department of Oral Physiology, School of Dentistry & Institute of Oral Bioscience, Chonbuk National University, Jeonju, South Korea.
authors.forename: Janardhan Prasad
authors.initials: JP
authors.lastname: Bhattarai
authors.affiliation: Department of Oral Physiology, School of Dentistry & Institute of Oral Bioscience, Chonbuk National University, Jeonju, South Korea.
authors.forename: Soo Joung
authors.initials: SJ
authors.lastname: Park
authors.affiliation: Department of Oral Biochemistry, School of Dentistry & Institute of Oral Bioscience, Chonbuk National University, Jeonju, South Korea.
authors.forename: Ho-Keun
authors.initials: HK
authors.lastname: Yi
authors.affiliation: Department of Oral Physiology, School of Dentistry & Institute of Oral Bioscience, Chonbuk National University, Jeonju, South Korea. Electronic address: skhan@jbnu.ac.kr.
authors.forename: Seong Kyu
authors.initials: SK
authors.lastname: Han
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology*; D005905:Glyburide / Q000494:pharmacology; D006801:Humans; D008964:Molar, Third; D018408:Patch-Clamp Techniques; D010513:Periodontal Ligament / Q000166:cytology*; D015221:Potassium Channels / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D015221:Potassium Channels; D012333:RNA, Messenger; D000255:Adenosine Triphosphate; D005905:Glyburide
keywords: Human periodontal ligament cell; Inside-out patch; K(ATP) channels