title: Inward rectifier potassium channels in the HL-1 cardiomyocyte-derived cell line.
abstract: HL-1 is a line of immortalized cells of cardiomyocyte origin that are a useful complement to native cardiomyocytes in studies of cardiac gene regulation. Several types of ion channel have been identified in these cells, but not the physiologically important inward rectifier K(+) channels. Our aim was to identify and characterize inward rectifier K(+) channels in HL-1 cells. External Ba(2+) (100 µM) inhibited 44 ± 0.05% (mean ± s.e.m., n = 11) of inward current in whole-cell patch-clamp recordings. The reversal potential of the Ba(2+)-sensitive current shifted with external [K(+)] as expected for K(+)-selective channels. The slope conductance of the inward Ba(2+)-sensitive current increased with external [K(+)]. The apparent Kd for Ba(2+) was voltage dependent, ranging from 15 µM at -150  mV to 148 µM at -75  mV in 120  mM external K(+). This current was insensitive to 10 µM glybenclamide. A component of whole-cell current was sensitive to 150 µM 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), although it did not correspond to the Ba(2+)-sensitive component. The effect of external 1 mM Cs(+) was similar to that of Ba(2+). Polymerase chain reaction using HL-1 cDNA as template and primers specific for the cardiac inward rectifier K(ir)2.1 produced a fragment of the expected size that was confirmed to be K(ir)2.1 by DNA sequencing. In conclusion, HL-1 cells express a current that is characteristic of cardiac inward rectifier K(+) channels, and express K(ir)2.1 mRNA. This cell line may have use as a system for studying inward rectifier gene regulation in a cardiomyocyte phenotype.
authors.affiliation: Cardiovascular Remodelling Group, Centre for Vision and Vascular Science, School of Medicine, Dentistry and Biomedical Sciences, Queen's University, Belfast, UK.
authors.forename: Dana
authors.initials: D
authors.lastname: Goldoni
authors.forename: YouYou
authors.initials: Y
authors.lastname: Zhao
authors.forename: Brian D
authors.initials: BD
authors.lastname: Green
authors.forename: Barbara J
authors.initials: BJ
authors.lastname: McDermott
authors.forename: Anthony
authors.initials: A
authors.lastname: Collins
mesh_terms: D000818:Animals; D001464:Barium / Q000378:metabolism; D002460:Cell Line; D002586:Cesium / Q000378:metabolism; D008564:Membrane Potentials; D051379:Mice; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D010641:Phenotype; D011188:Potassium / Q000378:metabolism*; D026902:Potassium Channel Blockers / Q000494:pharmacology; D024661:Potassium Channels, Inwardly Rectifying / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors
chemical_list: C489461:Kir2.1 channel; D026902:Potassium Channel Blockers; D024661:Potassium Channels, Inwardly Rectifying; D012333:RNA, Messenger; D002586:Cesium; D001464:Barium; D011188:Potassium