In:
American Journal of Physiology-Heart and Circulatory Physiology, American Physiological Society, Vol. 284, No. 1 ( 2003-01-01), p. H256-H267
Abstract:
We established HEK-293 cell lines that stably express functional canine ether-à-go-go-related gene (cERG) K + channels and examined their biophysical and pharmacological properties with whole cell patch clamp and 35 S-labeled MK-499 ([ 35 S]MK-499) binding displacement. Functionally, cERG current had the hallmarks of cardiac delayed rectifier K + current ( I Kr ). Channel opening was time- and voltage dependent with threshold near −40 mV. The half-maximum activation voltage was −7.8 ± 2.4 mV at 23°C, shifting to −31.9 ± 1.2 mV at 36°C. Channels activated with a time constant of 13 ± 1 ms at +20 mV, showed prominent inward rectification at depolarized potentials, were highly K + selective (Na + -to-K + permeability ratio = 0.007), and were potently inhibited by I Kr blockers. Astemizole, terfenadine, cisapride, and MK-499 inhibited cERG and human ERG (hERG) currents with IC 50 values of 1.3, 13, 19, and 15 nM and 1.2, 9, 14, and 21 nM, respectively, and competitively displaced [ 35 S]MK-499 binding from cERG and hERG with IC 50 values of 0.4, 12, 35, and 0.6 nM and 0.8, 5, 47, and 0.7 nM, respectively. cERG channels had biophysical properties appropriate for canine action potential repolarization and were pharmacologically sensitive to agents known to prolong QT. A novel MK-499 binding assay provides a new tool to detect agents affecting ERG channels.
Type of Medium:
Online Resource
ISSN:
0363-6135
,
1522-1539
DOI:
10.1152/ajpheart.00220.2002
Language:
English
Publisher:
American Physiological Society
Publication Date:
2003
detail.hit.zdb_id:
1477308-9
SSG:
12
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