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Thermodynamic Investigation of the Mechanism of Heat Production During Membrane Depolarization
The Journal of Physical Chemistry B ( IF 3.3 ) Pub Date : 2020-03-30 , DOI: 10.1021/acs.jpcb.9b11456
Behruz Bozorg 1, 2 , Michael Andersen Lomholt 1, 2 , Himanshu Khandelia 1, 2
Affiliation  

When an action potential passes through a neuron, heat is first produced and then reabsorbed by the neuronal membrane, resulting in a small measurable temperature spike. Here, we describe the thermodynamics and molecular features of the heat production using a coarse-grained molecular dynamics approach. We study a simple unicomponent lipid bilayer membrane surrounded by physiological salt solution with and without an external electric field, which represents an imbalanced charge across the membrane. We show that the temperature increases significantly upon removal of the electric field under constant pressure conditions. The potential energy converted to heat is initially stored mainly in the imbalanced ion distribution across the membrane and the elastic energy of the membrane has only a minor role to play. We demonstrate that the mechanism of heat production involves interaction between ions as well as lipid headgroup dipoles while the interactions between polar water molecules and lipid headgroup dipoles absorbs a considerable portion of such produced heat upon removal of the electric field. Our data provide novel thermodynamic insights into the molecular processes governing membrane reorganization upon discharging of lipid membranes and insight into energy metabolism in nerves.

中文翻译:

膜去极化过程中产热机理的热力学研究

当动作电位通过神经元时,首先会产生热量,然后再被神经元膜吸收,从而导致较小的可测量温度峰值。在这里,我们使用粗粒度的分子动力学方法描述了热量产生的热力学和分子特征。我们研究了一种简单的单组分脂质双层膜,其被生理盐溶液包围,带有或不带有外部电场,这表示整个膜上的电荷不平衡。我们表明,在恒定压力条件下去除电场后,温度显着升高。转换成热的势能最初主要存储在整个膜的不平衡离子分布中,而膜的弹性能仅发挥很小的作用。我们证明热量产生的机理涉及离子之间以及脂类头基偶极子之间的相互作用,而极性水分子和脂类头基偶极子之间的相互作用在去除电场时吸收了相当一部分这样产生的热量。我们的数据为脂膜释放后控制膜重组的分子过程提供了新颖的热力学见解,并深入了解了神经中的能量代谢。
更新日期:2020-03-30
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