Effect of Changes in the Intracellular Resistivity of Skeletal Muscle Fibre on Intracellular and Extracellular Potentials

Intensive muscle contractions are accompanied by metabolic changes that could affect the ionic composition of the cytoplasm of muscle fibre and thus its resistivity. We aim to study the effects of intracellular resistivity on intracellular action potentials (IAPs) and extracellular potentials (EPs). The Hodgkin-Huxley type mathematical model was used to simulate the intracellular processes in a muscle fibre. The spatial potential profile of the IAP was used to calculate the EP. The results showed that changes in the intracellular resistivity had practically no effect on the amplitude and shape of IAP in the temporal domain. The main effect was on the velocity of IAP propagation and thus on the length of IAP profile in the spatial domain. Changes in the length of the IAP profile affected the amplitude of the EPs above the end-plate region and above the middle of the fibre semilength to a similar extent. Effects of changes in the velocity of IAP propagation on the duration of the main negative phase of EPs were similar for detection above the end-plate region and above themiddle of the fibre semilength. The results will help in analysis of changes in the M-waves obtained during and after muscle activity.

Automated summary

Intensive muscle contractions can cause metabolic changes that affect intracellular resistivity and subsequently influence the propagation and length of intracellular action potentials (IAPs), as well as the amplitude of extracellular potentials (EPs). These findings are important for analyzing changes in M-waves during and after muscle activity.