K+ current distribution in rat sub-epicardial ventricular myocytes

Kimiaki Komukai, Fabien Brette, Tomoko T. Yamanushi, Clive H. Orchard

    Research output: Contribution to journalArticlepeer-review


    In the rat ventricle, the transient outward K+ current (ITO) is carried by heteromeric channels composed of Kv4.2 and Kv4.3. However its distribution in the cell membrane is unclear: immunohistochemical studies of Kv4.2 distribution in the cardiac ventricular cell membrane have given equivocal results, and there are no corresponding studies of Kv4.3. We therefore used detubulated cardiac cells to investigate the functional distribution of ITO between the t-tubules and surface membrane. ITO, the delayed rectifier (IK), the inward rectifier (IK1) and steady-state (ISS) K+ currents were monitored using the patch-clamp technique in control and formamide-treated (detubulated) cells from rat left ventricular sub-epicardium. Formamide treatment decreased cell capacitance by 20%, did not significantly change the density of ITO, IK or IK1 but decreased the density of ISS and L-type Ca current (ICa). These data suggest that ITO, IK, and IK1 are uniformly distributed between the surface and t-tubule membranes, but that ISS and ICa are concentrated in the t-tubules.
    Original languageEnglish
    Pages (from-to)532-538
    Number of pages6
    JournalPflügers Archiv European Journal of Physiology
    Issue number4
    Publication statusPublished - 2002


    • Ca current
    • Formamide
    • K current
    • Transverse tubule
    • Whole cell


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