Time, voltage and ionic concentration dependence of rectification of h-erg expressed in Xenopus oocytes.
The rapid delayed rectifier, IKr, is believed to have h-erg (human ether-à-go-go related gene) as its molecular basis. A recent study has shown that rectification of h-erg involves a rapid inactivation process that involves rapid closure of the external mouth of the pore or C-type inactivation. We measured the instantaneous current to voltage relationship for h-erg channels using the saponin permeabilized variation of the cut-open oocyte clamp technique. In contrast to C-type inactivation in other voltage-gated K+ channels, the rate of inactivation was strongly voltage dependent at depolarized potentials. This voltage dependence could be modulated independently of activation by increasing [K+]0 from 2 to 98 mM. These results suggest that inactivation of h-erg has its own intrinsic voltage sensor.
Wang
S
S
Department of Medicine, Duke University Medical Center, Durham, NC 27708-0281, USA.
Morales
M J
MJ
Liu
S
S
Strauss
H C
HC
Rasmusson
R L
RL
D000818:Animals; D027682:Cation Transport Proteins; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D051638:Ether-A-Go-Go Potassium Channels; D005260:Female; D005786:Gene Expression Regulation; D009865:Oocytes / Q000737:chemistry / Q000378:metabolism*; D011188:Potassium / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D015221:Potassium Channels / Q000096:biosynthesis* / Q000737:chemistry* / Q000187:drug effects; D024642:Potassium Channels, Voltage-Gated; D013997:Time Factors; D014982:Xenopus laevis / Q000502:physiology
D027682:Cation Transport Proteins; D051638:Ether-A-Go-Go Potassium Channels; C092509:KCNH6 protein, human; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D011188:Potassium