Inward rectifier potassium channels in the HL-1 cardiomyocyte-derived cell line

✍ Scribed by Dana Goldoni; YouYou Zhao; Brian D. Green; Barbara J. McDermott; Anthony Collins

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 170 KB
• Volume: 225
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.22278

✦ Synopsis

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 þ channels. Our aim was to identify and characterize inward rectifier K þ channels in HL-1 cells. External Ba 2þ (100 mM) inhibited 44 AE 0.05% (mean AE s.e.m., n ¼ 11) of inward current in whole-cell patch-clamp recordings. The reversal potential of the Ba 2þ -sensitive current shifted with external [K þ ] as expected for K þ -selective channels. The slope conductance of the inward Ba 2þ -sensitive current increased with external [K þ ]. The apparent Kd for Ba 2þ was voltage dependent, ranging from 15 mM at À150 mV to 148 mM at À75 mV in 120 mM external K þ . This current was insensitive to 10 mM glybenclamide. A component of whole-cell current was sensitive to 150 mM 4,4 0 -diisothiocyanatostilbene-2,2 0 -disulfonic acid (DIDS), although it did not correspond to the Ba 2þ -sensitive component. The effect of external 1 mM Cs þ was similar to that of Ba 2þ . 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 þ 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.