The effects of nucleotides and potassium channel openers on the SUR2A/Kir6.2 complex K+ channel expressed in a mammalian cell line, HEK293T cells

Pflugers Arch. 1998 Apr;435(5):595-603. doi: 10.1007/s004240050559.


The effects of potassium channel opening drugs and intracellular nucleotides on the ATP-sensitive K+ (KATP) channel composed of SUR2A and Kir6.2 in HEK293T cells were examined using the patch-clamp technique. The SUR2A/Kir6.2 channel was activated effectively by pinacidil, marginally by nicorandil but not by diazoxide. The pinacidil-activated channel currents were inhibited by glibenclamide with a Ki value of 160 nM. Upon formation of inside-out (I-O) patches, spontaneous openings of the channels appeared, which were inhibited by intracellular ATP (ATPi) equipotently in the presence and in the absence of intracellular Mg2+ (Mg2+i). The channel activity ran-down gradually in I-O patches. The run-down channels could be reactivated by ATPi only in the presence of Mg2+i. Uridine 5'-diphosphate (UDP) antagonized the ATPi-mediated inhibition of the channel activity before run-down. After run-down, UDP activated the channel without antagonizing ATPi-mediated channel inhibition. Thus, the SUR2A/Kir6.2 reproduced the major properties of the native cardiac KATP channel well in terms of nucleotide regulation and pharmacology, and therefore can be a useful tool with which to elucidate the molecular mechanisms characterizing the KATP channel.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP-Binding Cassette Transporters*
  • Adenosine Triphosphate / metabolism
  • Adenosine Triphosphate / pharmacology*
  • Cell Line
  • Diazoxide / pharmacology
  • Guanidines / pharmacology
  • Humans
  • Membrane Potentials / drug effects
  • Niacinamide / analogs & derivatives
  • Niacinamide / pharmacology
  • Nicorandil
  • Patch-Clamp Techniques
  • Pinacidil
  • Potassium Channels / biosynthesis
  • Potassium Channels / drug effects*
  • Potassium Channels, Inwardly Rectifying*
  • Receptors, Drug / biosynthesis
  • Receptors, Drug / drug effects*
  • Sulfonylurea Receptors
  • Uridine Diphosphate / pharmacology*


  • ABCC9 protein, human
  • ATP-Binding Cassette Transporters
  • Guanidines
  • Potassium Channels
  • Potassium Channels, Inwardly Rectifying
  • Receptors, Drug
  • Sulfonylurea Receptors
  • Niacinamide
  • Nicorandil
  • Uridine Diphosphate
  • Pinacidil
  • Adenosine Triphosphate
  • Diazoxide