Dresden 2017 – scientific programme

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BP: Fachverband Biologische Physik

BP 42: Neurosciences

BP 42.6: Talk

Wednesday, March 22, 2017, 16:45–17:00, ZEU 250

On collision of action potentials — •Christian Fillafer, Anne Paeger, and Matthias F. Schneider — Technische Universität Dortmund, Medizinische und Biologische Physik, Dortmund, Germany

It is a common incident in nature, that two waves or pulses run into each other head-on. The outcome of such an event is of special interest, because it allows conclusions about the underlying physical nature of the pulses. The present experimental study dealt with the head-on meeting of two action potentials (AP) in a single excitable plant cell (Chara braunii internode). The membrane potential was monitored at the two extremal regions of an excitable cell. In control experiments, an AP was excited electrically at either end of the cell cylinder. Subsequently, stimuli were applied simultaneously at both ends of the cell in order to generate two APs that met each other head-on. When two action potentials propagated into each other, the pulses did not penetrate but annihilated (N=14 experiments in n=4 cells). It was difficult to judge whether annihilation was complete or partial. A small data set indicated that both outcomes are possible. APs in excitable plant cells did not penetrate upon meeting head-on. In the classical electrical model, this behavior is attributed to relaxation of ion channel proteins. From an acoustic point of view, annihilation is a result of nonlinear material properties of the excitable medium. The present results indicate that APs in excitable animal and plant cells are similar nonlinear phenomena. Intriguingly, other excitation waves in biology (intracellular waves, cortical spreading depression, etc.) also annihilate upon collision and thus may be fundamentally related to action potentials.