Longitudinal and transversal propagation of excitation along the tubular system of rat fast-twitch muscle fibres studied by high speed confocal microscopy

摘要

Non-technical summaryContraction of the vertebrate skeletal muscle is dependent on the excitation of the highly specialized plasma membrane of individual muscle fibres. Most of the plasma membrane covers an extensive, structured network of narrow invaginating tubules, but little is known about how excitation propagates along the tubular network of mammalian skeletal muscle fibres in the radial and longitudinal directions with respect to the fibre axis. Here we show that excitation can take multiple pathways through the internal network of tubules in fast-twitch muscle fibres of the rat and determine the rates that excitation can spread within the internalized membrane tubules and show how this can change during muscle fatigue. Our results increase our understanding of mammalian skeletal muscle function in health, fatigue and some disease states.