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A novel anionic conductance affects action potential duration in isolated rat ventricular myocytes
Author(s) -
Spencer C Ian,
Uchida Wataru,
Kozlowski Roland Z
Publication year - 2000
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1038/sj.bjp.0703074
Subject(s) - extracellular , electrophysiology , patch clamp , biophysics , membrane potential , myocyte , chemistry , ion channel , conductance , voltage clamp , ventricular action potential , reversal potential , cardiac action potential , medicine , pharmacology , biochemistry , biology , repolarization , receptor , mathematics , combinatorics
Effects of extracellular anions were studied in electrophysiological experiments on freshly isolated rat ventricular myocytes. Under current‐clamp, action potential duration (APD) was prolonged by reducing the extracellular Cl − concentration and shortened by replacement of extracellular Cl − with I − . Under voltage‐clamp, membrane potential steps or ramps evoked an anionic background current (I AB ) carried by either Cl − , Br − , I − or NO 3 − . Activation of I AB was Ca 2+ ‐ and cyclic AMP‐independent, and was unaffected by cell shrinkage. I AB was insensitive to stilbene and fenamate anion transport blockers at concentrations that inhibit Ca 2+ ‐, cyclic AMP‐ and swelling‐activated Cl − currents in ventricular cells of other mammals. These results suggest that I AB may be carried by a novel class of Cl − channel. Correlation of anion substitution experiments on membrane current and action potentials revealed that I AB could play a major role in controlling rat ventricular APD. These findings have important implications for those studying cardiac Cl − channels as potential targets for novel antiarrythmic agents. British Journal of Pharmacology (2000) 129 , 235–238; doi: 10.1038/sj.bjp.0703074