Dose-dependent activation and block by bisG10, a K+ channel blocker, of mouse and frog skeletal muscle KATP channels.
The effects of a K+ channel blocker, bisG10, were examined on ATP-sensitive K+ (KATP) channels in membrane patches excised from mammalian and amphibian skeletal muscle fibres using the patch-clamp technique. At micromolar concentrations, bisG10, added on the intracellular side, induced a strong, reversible, flickery block of KATP channels. BisG10, added on the extracellular side, was about 100-fold less potent at inhibiting channel activity. At 10 nM, intracellular bisG10 increased KATP channel activity. This activation was independent of the presence of internal ATP or Mg2+. The inhibitory effect of bisG10 most likely arose from open-channel block whereas activation could result from more complex, indirect interactions.
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D005905:Glyburide / Q000494:pharmacology; D006146:Guanidines / Q000494:pharmacology*; D007004:Hypoglycemic Agents / Q000494:pharmacology*; D066298:In Vitro Techniques; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D051379:Mice; D018485:Muscle Fibers, Skeletal / Q000187:drug effects / Q000502:physiology*; D018482:Muscle, Skeletal / Q000187:drug effects / Q000502:physiology*; D026902:Potassium Channel Blockers; D015221:Potassium Channels / Q000502:physiology*; D011893:Rana esculenta
D006146:Guanidines; D007004:Hypoglycemic Agents; D026902:Potassium Channel Blockers; D015221:Potassium Channels; C005748:synthalin A; D000255:Adenosine Triphosphate; D008274:Magnesium; D005905:Glyburide