Dresden 2017 – scientific programme

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BP: Fachverband Biologische Physik

BP 42: Neurosciences

BP 42.8: Talk

Wednesday, March 22, 2017, 17:15–17:30, ZEU 250

On the Mechanical Component of an Action Potential — •Matan Mussel, Christian Fillafer, and Matthias F. Schneider — Technische Universität Dortmund, Dortmund, Germany

Action potentials (AP) in neurons are accompanied by a bi-phasic surface displacement, which is composed of swelling during depolarization and contraction during repolarization. This mechanical pulse (∼1–10 nm) has not received a satisfactory explanation up to date. Herein, we present results on mechanical changes during AP propagation in excitable plant cells (internodes of Chara Braunii). In a native Chara cell, the plasma membrane is tightly pressed against the cell wall by turgor pressure (∼6 bar). In order to directly study deformations of the cell surface, turgor pressure was reduced by osmosis until the plasma membrane detached from the cell wall. Upon excitation of an AP, the surface displaced by ∼1–10 um. This mechanical deflection (i) propagated with the same velocity as the electrical pulse (∼10 mm/s), (ii) was reversible and (iii) in most cases of biphasic nature. We propose a mechanical model that describes these shape transformations as an interplay between the surface forces and the pressure difference across the surface. Our model captures the essence of the cell shape dynamics and makes testable predictions about the underlying mechanism.