Effect of the Ito activator NS5806 on cloned Kv4 channels depends on the accessory protein KChIP2
作者:A Lundby、T Jespersen、N Schmitt、M Grunnet、S-P Olesen、JM Cordeiro、K Calloe
DOI:10.1111/j.1476-5381.2010.00859.x
日期:2010.8
BACKGROUND AND PURPOSEThe compound NS5806 increases the transient outward current (Ito) in canine ventricular cardiomyocytes and slows current decay. In human and canine ventricle, Ito is thought to be mediated by KV4.3 and various ancillary proteins, yet, the exact subunit composition of Ito channels is still debated. Here we characterize the effect of NS5806 on heterologously expressed putative Ito channel subunits and other potassium channels.EXPERIMENTAL APPROACHCloned KV4 channels were co‐expressed with KChIP2, DPP6, DPP10, KCNE2, KCNE3 and KV1.4 in Xenopus laevis oocytes or CHO‐K1 cells.KEY RESULTSNS5806 increased KV4.3/KChIP2 peak current amplitudes with an EC50 of 5.3 ± 1.5µM and significantly slowed current decay. KCNE2, KCNE3, DPP6 and DPP10 modulated KV4.3 currents and the response to NS5806, but current decay was slowed only in complexes containing KChIP2. The effect of NS5806 on KV4.2 was similar to that on KV4.3, and current decay was only slowed in presence of KChIP2. However, for KV4.1, the slowing of current decay by NS5806 was independent of KChIP2. KV1.4 was strongly inhibited by 10 µM NS5806 and KV1.5 was inhibited to a smaller extent. Effects of NS5806 on kinetics of currents generated by KV4.3/KChIP2/DPP6 with KV1.4 in oocytes could reproduce those on cardiac Ito in canine ventricular myocytes. KV7.1, KV11.1 and Kir2 currents were unaffected by NS5806.CONCLUSION AND IMPLICATIONSNS5806 modulated KV4 channel gating depending on the presence of KChIP2, suggesting that NS5806 can potentially be used to address the molecular composition as well as the physiological role of cardiac Ito.