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Fast Pseudo-Periodic Oscillation in the Rat Brain Voltage-gated Sodium Channel α Subunit

Majumdar, S and Sikdar, SK (2005) Fast Pseudo-Periodic Oscillation in the Rat Brain Voltage-gated Sodium Channel α Subunit. In: Journal of Membrane Biology, 208 (1). pp. 1-14.

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In the work reported here, we have investigated the changes in the activation and fast inactivation properties of the rat brain voltage-gated sodium channel $(rNa_v 1.2a)$ $\alpha$ subunit, expressed heterologously in the Chinese Hamster Ovary (CHO) cells, by short depolarizing prepulses (10 – 1000 ms). The time constant of recovery from fast inactivation $(\top_f_a_s_t)$ and steady-state parameters for activation and inactivation varied in a pseudo-oscillatory fashion with the duration and amplitude of a sustained prepulse. A consistent oscillation was observed in most of the steady-state and non-inactivating current parameters with a time period close to 225 ms, although a faster oscillation of time period 125 ms was observed in the $\top_f_a_s_t$. The studies on the non-inactivating current and steady-state activation indicate that the phase of oscillation varies from cell to cell. Co-expression of the $\beta$1 subunit with the α subunit channel suppressed the oscillation in the charge movement per single channel and free energy of steady-state inactivation, although the oscillation in the half steady-state inactivation potential remained unaltered. Incidentally, the frequencies of oscillation in the sodium channel parameters (4–8 Hz) correspond to the theta component of network oscillation. This fast pseudo-oscillatory mechanism, together with the slow pseudo-oscillatory mechanism found in these channels earlier, may contribute to the oscillations in the firing properties observed in various neuronal subtypes and many pathological conditions.

Item Type: Journal Article
Publication: Journal of Membrane Biology
Publisher: Springer New York
Additional Information: The Copyright belongs to Springer New York.
Keywords: Voltage gated sodium channel ; Weig-ted wavelet analysis ; Whole-cell patch-clamp ; Epilepsy – Oscillation;
Department/Centre: Division of Biological Sciences > Molecular Biophysics Unit
Date Deposited: 13 Apr 2006
Last Modified: 27 Aug 2008 11:53
URI: http://eprints.iisc.ac.in/id/eprint/6282

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