Time, voltage and ionic concentration dependence of rectification of h‐erg expressed in Xenopus oocytes

[摘要]

The rapid delayed rectifier, I_Kr is believed to have h-erg (uman ther-à-go-go elated ene) 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⁺]_o from 2 to 98 mM. These results suggest that inactivation of h-erg has its own intrinsic voltage sensor.

[学科分类] 生物化学/生物物理

[关键词] Potassium;Delayed rectifier;Repolarization;Cardiac myocyte