Regensburg 2004 – scientific programme

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AKB: Biologische Physik

AKB 50: Poster Session "Biological Physics"

AKB 50.45: Poster

Friday, March 12, 2004, 10:30–13:00, B

Gating charge effects for nerve excitation — •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 passage of ions trough the cell membrane, but they also contribute to the membrane capacity, since the switching of the channel gates between an open and a closed configuration is always connected with movement of charge within the cell membrane. Especially, in case of moderately large densities of ion channels, which are found, for example, in the nodes of Ranvier, this may play a crucial role for nerve excitation. Our model system is a modified Hodgkin-Huxley model which takes into account the change in the membrane capacity. Additional terms, which are proportional to the number of ion channels resp. the number of gates, extend the original Hodgkin-Huxley model and allow the consideration of a – due to the gating charges – time-dependent membrane capacity. Surprisingly, the gating charge do not dramatically change the excitation behavior even for extreme dense ion channel assemblies, instead, the membrane capacity at rest exhibits a bell-shaped dependence on the ion channel density. This work is supported by DFG (SFB 486).