title: Acute exposure of methylglyoxal leads to activation of KATP channels expressed in HEK293 cells.
abstract: OBJECTIVE
  Highly reactive carbonyl methylglyoxal (MGO) is one of the metabolites excessively produced in diabetes. We have showed that prolonged exposure of vascular smooth muscle cells to MGO leads to instability of the mRNA encoding ATP-sensitive potassium (KATP) channel. In the present study we investigated the effects of MGO on the activity of KATP channels.
  
  
  METHODS
  Kir6.1/ SUR2B, Kir6.2/SUR2B or Kir6.2Δ36 (a truncated Kir6.2 isoform) alone was expressed in HEK293 cells. Whole-cell currents were recorded in the cells with an Axopatch 200B amplifier. Macroscopic currents and single-channel currents were recorded in giant inside-out patches and normal inside-out patches, respectively. Data were analyzed using Clampfit 9 software.
  
  
  RESULTS
  The basal activity of Kir6.1/SUR2B channels was low. The specific KATP channel opener pinacidil (10 μmol/L) could fully activate Kir6.1/SUR2B channels, which was inhibited by the specific KATP channel blocker glibenclamide (10 μmol/L). MGO (0.1-10 mmol/L) dose-dependently activated Kir6.1/SUR2B channels with an EC50 of 1.7 mmol/L. The activation of Kir6.1/SUR2B channels by MGO was reversible upon washout, and could be inhibited completely by glibenclamide. Kir6.2Δ36 channels expressed in HEK293 cells could open automatically, and the channel activity was enhanced in the presence of MGO (3 mmol/L). Single channel recordings showed that MGO (3 mmol/L) markedly increased the open probability of Kir6.1/SUR2B channels, leaving the channel conductance unaltered.
  
  
  CONCLUSIONS
  Acute application of MGO activates KATP channels through direct, non-covalent and reversible interactions with the Kir6 subunits.
authors.affiliation: Now in Center for Neuroscience & Regeneration/Rehabilitation Research, Department of Neurology, Yale University School of Medicine & Veterans Affairs Connecticut Healthcare System, USA.
authors.forename: Yang
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Biology, Georgia State University, Atlanta, GA 30302-4010, USA.
authors.forename: Anuhya S
authors.initials: AS
authors.lastname: Konduru
authors.affiliation: Department of Biology, Georgia State University, Atlanta, GA 30302-4010, USA.
authors.forename: Ningren
authors.initials: N
authors.lastname: Cui
authors.affiliation: Department of Biology, Georgia State University, Atlanta, GA 30302-4010, USA.
authors.forename: Lei
authors.initials: L
authors.lastname: Yu
authors.affiliation: Department of Biology, Georgia State University, Atlanta, GA 30302-4010, USA.
authors.forename: Timothy C
authors.initials: TC
authors.lastname: Trower
authors.affiliation: Department of Biology, Georgia State University, Atlanta, GA 30302-4010, USA.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Shi
authors.affiliation: Department of Biology, Georgia State University, Atlanta, GA 30302-4010, USA.
authors.forename: Yun
authors.initials: Y
authors.lastname: Shi
authors.affiliation: Department of Biology, Georgia State University, Atlanta, GA 30302-4010, USA.
authors.forename: Chun
authors.initials: C
authors.lastname: Jiang
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006801:Humans; D054086:KATP Channels / Q000819:agonists* / Q000096:biosynthesis / Q000378:metabolism*; D051379:Mice; D011765:Pyruvaldehyde / Q000008:administration & dosage*; D051381:Rats; D013997:Time Factors
chemical_list: D054086:KATP Channels; D011765:Pyruvaldehyde