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XB-ART-1504
Biophys J 2005 Nov 01;895:3026-41. doi: 10.1529/biophysj.105.059378.
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Time- and voltage-dependent components of Kv4.3 inactivation.

Wang S , Bondarenko VE , Qu YJ , Bett GC , Morales MJ , Rasmusson RL , Strauss HC .


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Kv4.3 inactivation is a complex multiexponential process, which can occur from both closed and open states. The fast component of inactivation is modulated by the N-terminus, but the mechanisms mediating the other components of inactivation are controversial. We studied inactivation of Kv4.3 expressed in Xenopus laevis oocytes, using the two-electrode voltage-clamp technique. Inactivation during 2000 ms pulses at potentials positive to the activation threshold was described by three exponents (46 +/- 3, 152 +/- 13, and 930 +/- 50 ms at +50 mV, n = 7) whereas closed-state inactivation (at potentials below threshold) was described by two exponents (1079 +/- 119 and 3719 +/- 307 ms at -40 mV, n = 9). The fast component of open-state inactivation was dominant at potentials positive to -20 mV. Negative to -30 mV, the intermediate and slow components dominated inactivation. Inactivation properties were dependent on pulse duration. Recovery from inactivation was strongly dependent on voltage and pulse duration. We developed an 11-state Markov model of Kv4.3 gating that incorporated a direct transition from the open-inactivated state to the closed-inactivated state. Simulations with this model reproduced open- and closed-state inactivation, isochronal inactivation relationships, and reopening currents. Our data suggest that inactivation can proceed primarily from the open state and that multiple inactivation components can be identified.

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Species referenced: Xenopus laevis
Genes referenced: kcnd3

References [+] :
Aldrich, A reinterpretation of mammalian sodium channel gating based on single channel recording. , Pubmed