Kinetic changes in tetanic Ca2+ transients in enzymatically dissociated muscle fibres under repetitive stimulation

摘要

Non-technical summaryThe transient and progressive decrease in skeletal muscle performance during contraction is known as fatigue. One of the phenomena associated with fatigue is an alteration in the excitation–contraction coupling mechanism. Using isolated muscle fibres loaded with the fast Ca²⁺ dye Magfluo-4, we have found that after a protocol of repetitive stimulation there are alterations in the ability of the fibres to release and reuptake Ca²⁺, which are more evident and rapidly established in fast fibres compared to slow ones. All alterations were reversed after several minutes of rest and were not related to a phenomenon of inactivation of Ca²⁺ release. These data increase our knowledge of the events present during muscle fatigue and will help understand the mechanisms responsible for them.