Force Measurements From Myofibril to Filament.

Steven Marston

doi:10.3389/fphys.2021.817036

Abstract

Contractility, the generation of force and movement by molecular motors, is the hallmark of all muscles, including striated muscle. Contractility can be studied at every level of organization from a whole animal to single molecules. Measurements at sub-cellular level are particularly useful since, in the absence of the excitation-contraction coupling system, the properties of the contractile proteins can be directly investigated; revealing mechanistic details not accessible in intact muscle. Moreover, the conditions can be manipulated with ease, for instance changes in activator Ca2+, small molecule effector concentration or phosphorylation levels and introducing mutations. Subcellular methods can be successfully applied to frozen materials and generally require the smallest amount of tissue, thus greatly increasing the range of possible experiments compared with the study of intact muscle and cells. Whilst measurement of movement at the subcellular level is relatively simple, measurement of force is more challenging. This mini review will describe current methods for measuring force production at the subcellular level including single myofibril and single myofilament techniques.

Highlights

The production of force and movement by molecular motors is the essence of contractility
Contractility is usually measured in intact small muscle strips or single myocytes where contractility is dependent on the EC coupling system and neural and humoral stimulation that act on the Ca2+-regulation of the contractile apparatus itself
To extend force measurements from muscle to single myofibrils or even single filaments requires a number of technological advances that were exceptional in the 1990s when these methods were first developed but have become mainstream

Summary

Introduction

The production of force and movement by molecular motors is the essence of contractility. Contractility measurements at the sub cellular level in myofibrils and single filaments offer advantages that make their development worthwhile. To extend force measurements from muscle to single myofibrils or even single filaments requires a number of technological advances that were exceptional in the 1990s when these methods were first developed but have become mainstream.

Results

Conclusion