Kang Kevin H, Schneider Matthias F
Department of Physics, Technical University of Dortmund, Dortmund, Germany.
Eur Phys J E Soft Matter. 2020 Feb 5;43(2):8. doi: 10.1140/epje/i2020-11903-x.
Environmental temperature has a well-conserved effect on the pulse velocity and excitability of excitable biological systems. The consistency suggests that the cause originates from a fundamental principle. A physical (hydrodynamic) approach has proposed that the thermodynamic state of the hydrated interface (e.g., plasma membrane) determines the pulse behavior. This implies that the temperature effect happens because the environmental temperature affects the state of the interface in any given system. To test the hypothesis, we measured temperature-dependent phase diagrams of a lipid monolayer and studied the properties of nonlinear acoustic pulses excited along the membrane. We observed that the membrane in the fluid-gel transition regime exhibited lower compressibility (i.e., stiffer) overall with increasing temperature. Nonlinear pulses excited near the transition state propagated with greater velocity with increasing temperature, and these observations were consistent with the compressibility profiles. Excitability was suppressed significantly or ceased completely when the state departed too far from the transition regime either by cooling or by heating. The overall correlation between the pulses in the membrane and in living systems as a function of temperature supports the view that the thermodynamic state of the interface and phase transition are the key to understanding pulse propagation in excitable systems.
环境温度对可兴奋生物系统的脉冲速度和兴奋性具有高度保守的影响。这种一致性表明其原因源自一个基本原理。一种物理（流体动力学）方法提出，水合界面（如质膜）的热力学状态决定了脉冲行为。这意味着温度效应的发生是因为环境温度影响了任何给定系统中界面的状态。为了验证这一假设，我们测量了脂质单层的温度相关相图，并研究了沿膜激发的非线性声脉冲的特性。我们观察到，在流体 - 凝胶转变区域的膜随着温度升高总体上表现出更低的压缩性（即更硬）。在转变状态附近激发的非线性脉冲随着温度升高传播速度更快，并且这些观察结果与压缩性曲线一致。当通过冷却或加热使状态偏离转变区域太远时，兴奋性会显著受到抑制或完全停止。膜中的脉冲与生物系统中的脉冲之间随温度变化的整体相关性支持了这样一种观点，即界面的热力学状态和相变是理解可兴奋系统中脉冲传播的关键。
