Single HERG delayed rectifier K+ channels expressed in Xenopus oocytes.
HERG is a K+ channel with properties similar to the rapidly activating component (I(Kr)) of delayed rectifier K+ current, which is important for repolarization of human cardiac myocytes. In this study, we have characterized the single-channel properties of HERG expressed in Xenopus oocytes. Currents were measured in cell-attached patches with an extracellular K concentration of 120 mM. The single HERG channel conductance, determined at test potentials between -50 and -110 mV, was 12.1 +/- 0.6 pS. At positive test potentials (+40 to +80 mV), the probability of channel opening was low and slope conductance was 5.1 +/- 0.6 pS. The mean channel open times at -90 mV were 2.9 +/- 0.5 and 11.8 +/- 1.0 ms, and the mean channel closed times were 0.54 +/- 0.02 and 14.5 +/- 5.3 ms. Single HERG channels were blocked by MK-499, a class III antiarrhythmic agent that blocks I(Kr) in cardiac myocytes. The development of block was more rapid in inside-out patches than in cell-attached patches or in whole cell recordings, indicating that block occurs from the cytoplasmic side of the membrane. The single-channel properties of HERG are similar to I(Kr) channels of isolated cardiac myocytes, which provides further evidence that HERG proteins coassemble to form I(Kr) channels.
Zou
A
A
Cardiology Division, University of Utah Health Sciences Center, Salt Lake City 84132, USA.
Curran
M E
ME
Keating
M T
MT
Sanguinetti
M C
MC
D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology; D001578:Benzopyrans / Q000494:pharmacology; D027682:Cation Transport Proteins; D004268:DNA-Binding Proteins; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; D006801:Humans; D066298:In Vitro Techniques; D015640:Ion Channel Gating; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D010880:Piperidines / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D015221:Potassium Channels / Q000096:biosynthesis / Q000502:physiology*; D024642:Potassium Channels, Voltage-Gated; D018075:RNA, Complementary; D013997:Time Factors; D015534:Trans-Activators; D000071230:Transcriptional Regulator ERG; D014982:Xenopus laevis
D000889:Anti-Arrhythmia Agents; D001578:Benzopyrans; D027682:Cation Transport Proteins; D004268:DNA-Binding Proteins; C072312:ERG protein, human; D000072237:ERG1 Potassium Channel; D051638:Ether-A-Go-Go Potassium Channels; C000606913:KCNH2 protein, human; C092509:KCNH6 protein, human; D010880:Piperidines; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D018075:RNA, Complementary; D015534:Trans-Activators; D000071230:Transcriptional Regulator ERG; C087257:L 706000; D011188:Potassium