COMSOL models of fluid flow in the sarcomere

A highly organized and densely packed lattice of molecular machinery within the sarcomeres of muscle cells powers contraction. Although many of the proteins that drive contraction have been studied extensively, the mechanical impact of fluid shearing within the lattice of molecular machinery has received minimal attention. It was recently proposed that fluid flow augments substrate transport in the sarcomere, however, this analysis used analytical models of fluid flow in the molecular machinery that could not capture its full complexity. By building a finite element model of the sarcomere, we estimate the explicit flow field, and contrast it with analytical models. Our results demonstrate that viscous drag forces on sliding filaments are surprisingly small in contrast to the forces generated by single myosin molecular motors. This model also indicates that the energetic cost of fluid flow through viscous shearing with lattice proteins is likely minimal. The model also highlights a steep...

肌细胞肌节（sarcomere）内部存在高度规整、致密排列的分子机器晶格，该结构为肌肉收缩提供动力。尽管诸多驱动肌肉收缩的蛋白质已被广泛研究，但分子机器晶格内流体剪切作用的力学效应却极少受到关注。此前虽有研究提出流体流动可促进肌节内的底物转运，但该分析所采用的分子机器内流体流动解析模型，无法完整捕捉其真实的复杂特性。本研究通过构建肌节的有限元模型（finite element model），求解得到明确的流场分布，并与解析模型进行对比。研究结果表明，与单个肌球蛋白（myosin）分子马达产生的作用力相比，作用于滑动丝的粘性拖拽力出人意料地微弱。该模型同时显示，流体因与晶格蛋白发生粘性剪切而产生的流动能量消耗极微。本模型还揭示了一种显著的……