近日，美国哈佛大学的Suraj Shankar与L. Mahadevan合作并取得一项新进展。经过不懈努力，他们揭示肌肉纤维的活性液压和奇弹性。相关研究成果已于2024年7月8日在国际知名学术期刊《自然—物理学》上发表。

为了理解收缩速率和肌肉能量学的限制，该研究团队构建了一个粗粒度的多尺度模型，将肌肉描述为一个活性海绵。研究人员对跨物种和肌肉类型的现有实验的分析，强调了空间异质性应变和局部体积变形的重要性。最小理论模型显示了收缩如何诱导细胞内流体流动，和动力活性液压振荡，从而产生超快肌肉收缩的极限。

研究人员进一步证明，由于肌肉的活性和各向异性，肌肉的粘弹性响应自然是非互易的或奇数的。与之前基于时间周期的描述相比，这使得仅从空间应变的周期循环中产生肌肉动力的替代模式成为可能。这项研究工作提出了一种修正的肌肉动力学观点，凸显软液压动力的多尺度时空起源，对生理学、生物力学和运动有潜在的影响。

据悉，肌肉是一个复杂的、分层组织的、软的可收缩性引擎。

附：英文原文

Title: Active hydraulics and odd elasticity of muscle fibres

Author: Shankar, Suraj, Mahadevan, L.

Issue&Volume: 2024-07-08

Abstract: Muscle is a complex, hierarchically organized, soft contractile engine. To understand the limits on the rate of contraction and muscle energetics, we construct a coarse-grained multiscale model that describes muscle as an active sponge. Our analysis of existing experiments across species and muscle types highlights the importance of spatially heterogeneous strains and local volumetric deformations. Our minimal theoretical model shows how contractions induce intracellular fluid flow and power active hydraulic oscillations, yielding the limits of ultrafast muscular contractions. We further demonstrate that the viscoelastic response of muscle is naturally non-reciprocal—or odd—owing to its active and anisotropic nature. This enables an alternate mode of muscular power generation from periodic cycles in spatial strain alone, contrasting with previous descriptions based on temporal cycles. Our work suggests a revised view of muscle dynamics that emphasizes the multiscale spatiotemporal origins of soft hydraulic power, with potential implications for physiology, biomechanics and locomotion.

DOI: 10.1038/s41567-024-02540-x

Source: https://www.nature.com/articles/s41567-024-02540-x