Dresden 2006 – wissenschaftliches Programm

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AKB: Biologische Physik

AKB 18: Ion Channels and Nanopores

AKB 18.2: Vortrag

Mittwoch, 29. März 2006, 16:00–16:15, ZEU 255

Gating charge effects in excitable membranes — •Gerhard Schmid, Igor Goychuk, and Peter Hänggi — Institut für Physik, Universität Augsburg

Voltage dependent ion channels mainly determine the electric properties of axonal cell membranes. The ion channels thereby do not only allow the passage of ions trough the cell membrane but they also contribute to the additional charging of the cell membrane resulting in the so-called capacitance loading. The switching of the channel gates between an open and a closed configuration is always connected with movement of gating charge within the cell membrane. At the beginning of an action potential the gating current is opposite to the direction of the ion current through the membrane. Therefore the excitability is reduced due to capacitance loading. Our stochastic Hodgkin-Huxley modelling takes into account both, channel noise – the fluctuations of the number of open ion channels [1] – and the capacitance fluctuations due to gating charge. We investigate the spiking dynamics of small membrane patches and analyze the statistics of the spontaneous spiking. In doing so, we find that such gating charge effects yield a drastic reduction of the spontaneous spiking rate. This work is supported by DFG (SFB 486).

[1] G. Schmid, I. Goychuk, P. Hänggi, Europhys. Lett. 56, 22-28 (2001).