Role of a Tetraethylammonium-Sensitive Component of Potassium Currents in High-Frequency Tonic Impulsation Generated by Rat Retinal Ganglion Cells

Authors: Kuznetsov, K.¹; Maslov, V.²; Fedulova, S.²; Veselovsky, N.²

Source: Neurophysiology, Volume 43, Number 1, July 2011 , pp. 8-13(6)

Publisher: Springer

Abstract:

Using the voltage/current clamp technique in the whole-cell configuration, we studied the role of the highly tetraethylammonium (TEA) -sensitive component of integral potassium current in the generation of high-frequency tonic impulsation by rat retinal ganglion cells (RGCs). Application of 0.5 mM TEA led to a decrease in the frequency of evoked tonic impulsation by RGCs by 63% (from 55 ± 10 sec^-1 in the control to 26 ± 5 sec^-1 in the presence of the blocker; n = 11). In this case, the duration of single action potentials at the level of 50% their amplitude increased by 64% (from 1.1 ± 0.1 to 1.8 ± 0.1 msec; n = 11), the rate of repolarization decreased by 54% (from −101 ± 9 to −46 ± 5 mV/msec; n = 11), and the amplitude of afterhyperpolarization dropped by 62% (from −16 ± 2 to −6 ± 2 mV; n = 11). Upon the action of 0.5 mM TEA, the amplitude of the integral potassium current in RGCs decreased; the current component sensitive to the above blocker was equal to 0.41 ± 0.05 nA (n = 6), while the respective value in the control was 1.62 ± 0.14 nA (n = 12). Thus, a moderate (on average, by 25%) decrease in the amplitude of the above potassium current significantly influenced the characteristics of impulse activity generated by RGCs. The TEA-sensitive component of the current was similar to the Kv3.1/Kv3.2 potassium current described earlier. The obtained data are indicative of the key role of the highly TEA-sensitive component of the potassium current (passed probably via Kv3.1/Kv3 channels) in high-frequency tonic activity generated by RGCs.

Keywords: retinal ganglion cells; high-frequency tonic impulsation; potassium current; tetraethylammonium

Document Type: Research article

DOI: http://dx.doi.org/10.1007/s11062-011-9190-8

Affiliations: 1: Bogomolets Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine, Email: kir.kuznet@gmail.com 2: Bogomolets Institute of Physiology, National Academy of Sciences of Ukraine, Kyiv, Ukraine

Publication date: 2011-07-01

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• In this Subject: Anatomy & Physiology ,  Neurology & Psychiatry ,  Pathology
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