Cell Surface Deformation during an Action Potential.

Area of Science:

• Cellular Biophysics
• Plant Physiology

Background:

• Cellular excitation, particularly action potentials, is often linked to mechanical alterations within cells and tissues.
• Understanding the physical basis of cellular excitability is crucial for various biological processes.

Purpose of the Study:

• To investigate and confirm that single plant cells undergo mechanical deformation during an action potential.
• To characterize the nature and properties of the associated mechanical changes in the cell surface.

Main Methods:

• Utilizing Chara braunii internodes to observe cell surface displacements during electrical excitation.
• Employing micropipette aspiration experiments to assess transient mechanical changes in the cell cortex.
• Conducting theoretical analysis to model the observed mechanical phenomena.

Main Results:

• Excitation of Chara braunii cells induced micrometer-range out-of-plane surface displacements coinciding with the action potential's depolarization phase.
• The mechanical response propagated at the same velocity as the electrical signal (~10 mm s⁻¹), was reversible, and often biphasic.
• Micropipette aspiration confirmed transient mechanical changes in the cell cortex, independent of actin-myosin motility.

Conclusions:

• The observed cellular deformations can be explained by reversible alterations in cell surface mechanical properties, including transmembrane pressure, surface tension, and bending rigidity.
• These findings provide evidence for a physical link between electrical excitation and mechanical changes at the cellular level.
• The study contributes to the understanding of the physical mechanisms underlying cellular excitability.