Intramembrane charge movement associated with endogenous K+ channel activity in HEK-293 cells.
1. The use of molecular biology in combination with electrophysiology in the HEK-293 cell line has given fascinating insights into neuronal ion channel function. Nevertheless, to fully understand the properties of channels exogenously expressed in these cells, a detailed evaluation of endogenous channels is indispensable. 2. Previous studies have shown the expression of endogenous voltage-gated K+, Ca2+, and Cl- channels and this predicts that changes in membrane potential will cause intramembrane charge movement, though this gating charge translocation remain undefined. Here, we confirm this prediction by performing patch-clamp experiments to record ionic and gating currents. Our data show that HEK-293 cells express at least two types of K+-selective endogenous channels which sustain the majority of the ionic current, and exclude a significant contribution from Ca2+ and Cl- channels to the whole-cell current. 3. Gating currents were unambiguously resolved after ionic current blockade enabling this first report of intramembrane charge movement in HEK-293 cells arising entirely from endogenous K+ channel activity, and providing valuable information concerning the activation mechanism of voltage-gated K+ channels in these cells.
Avila
Guillermo
G
Department of Biochemistry, Center for Research and Advanced Studies of the National Polytechnic Institute (Cinvestav-IPN), Mexico City, Mexico.
Sandoval
Alejandro
A
Felix
Ricardo
R
D015220:Calcium Channels / Q000378:metabolism; D002122:Calcium Chloride / Q000494:pharmacology; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism*; D002586:Cesium / Q000494:pharmacology; D018118:Chloride Channels / Q000378:metabolism; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology*; D007477:Ions / Q000378:metabolism*; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009544:Niflumic Acid / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers / Q000494:pharmacology; D024642:Potassium Channels, Voltage-Gated / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011189:Potassium Chloride / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology; D019789:Tetraethylammonium / Q000494:pharmacology
D015220:Calcium Channels; D018118:Chloride Channels; D007477:Ions; D026902:Potassium Channel Blockers; D024642:Potassium Channels, Voltage-Gated; D002586:Cesium; D012965:Sodium Chloride; D009544:Niflumic Acid; D019789:Tetraethylammonium; D011189:Potassium Chloride; D002122:Calcium Chloride