Identification and pharmacological characterization of sarcolemmal ATP-sensitive potassium channels in the murine atrial HL-1 cell line.
Activation of ATP-sensitive potassium (KATP) channels is known to have cardioprotective effects during periods of ischemia and reperfusion, making these channels important targets for clinical drug discovery. Using electrophysiological techniques we identify KATP channels in a mouse atrial cell line (HL-1). HL-1 KATP channels exhibited a concentration-dependent inhibition by ATP (IC50 = 23.3 +/- 3.2 microM), a unitary single-channel conductance of 55 pS, and sensitivity to the isoform-specific KATP channel opener P1075 and inhibitor HMR1098. Adenoviral infection of a dominant-negative Kir6.2 subunit significantly reduced the P1075-sensitive sarcKATP current. Taken together, the data indicate that HL-1 KATP channels are composed of sulfonylurea receptor isoform SUR2A coupled to the pore-forming Kir6.2 subunit--the molecular makeup of sarcKATP channels found in native cardiac myocytes. Pharmacological activation of HL-1 cell KATP channels also resulted in action potential shortening. Using the membrane potential-sensitive dye DiBac4(3), we demonstrated that the sarcKATP channel opener P1075 (20 microM) produced a concentration-dependent hyperpolarization of a monolayer of HL-1 cells that could be reversed by channel inhibition with HMR1098 (20 microM). We conclude that the HL-1 cells are an excellent cell line for studying cardiac sarcKATP channels, and these cells may also provide an important tool for the testing of novel pharmacological modulators of KATP channels in fluorescence-based assays.
Fox
Jocelyn E Manning
JE
Department of Pharmacology, University of Alberta, Edmonton, Alberta, Canada. j.manningfox@utoronto.ca
Jones
Lynn
L
Light
Peter E
PE
D018528:ATP-Binding Cassette Transporters / Q000235:genetics; D000200:Action Potentials; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000818:Animals; D001549:Benzamides / Q000494:pharmacology; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D006146:Guanidines / Q000494:pharmacology; D006325:Heart Atria / Q000378:metabolism; D015640:Ion Channel Gating; D051379:Mice; D009206:Myocardium / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics; D011725:Pyridines / Q000494:pharmacology; D011955:Receptors, Drug / Q000235:genetics; D012508:Sarcolemma / Q000378:metabolism*; D064233:Sulfonylurea Receptors; D014162:Transfection; D000099161:Kcnj11 Channel
D018528:ATP-Binding Cassette Transporters; D000255:Adenosine Triphosphate; D001549:Benzamides; D006146:Guanidines; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D011725:Pyridines; D011955:Receptors, Drug; D064233:Sulfonylurea Receptors; D000099161:Kcnj11 Channel; C577511:Abcc9 protein, mouse; C073896:N-cyano-N'-(1,1-dimethylpropyl)-N''-(3-pyridinyl)guanidine; C410297:HMR 1098