Human skeletal muscle plasmalemma alters its structure to change its Ca2+-handling following heavy-load resistance exercise

Nat Commun. 2017 Feb 13:8:14266. doi: 10.1038/ncomms14266.

Abstract

High-force eccentric exercise results in sustained increases in cytoplasmic Ca2+ levels ([Ca2+]cyto), which can cause damage to the muscle. Here we report that a heavy-load strength training bout greatly alters the structure of the membrane network inside the fibres, the tubular (t-) system, causing the loss of its predominantly transverse organization and an increase in vacuolation of its longitudinal tubules across adjacent sarcomeres. The transverse tubules and vacuoles displayed distinct Ca2+-handling properties. Both t-system components could take up Ca2+ from the cytoplasm but only transverse tubules supported store-operated Ca2+ entry. The retention of significant amounts of Ca2+ within vacuoles provides an effective mechanism to reduce the total content of Ca2+ within the fibre cytoplasm. We propose this ability can reduce or limit resistance exercise-induced, Ca2+-dependent damage to the fibre by the reduction of [Ca2+]cyto to help maintain fibre viability during the period associated with delayed onset muscle soreness.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Calcium / metabolism*
  • Cell Membrane / metabolism*
  • Cytoplasm / metabolism
  • Exercise / physiology*
  • Humans
  • Male
  • Microscopy, Confocal
  • Muscle Contraction / physiology
  • Muscle Fibers, Skeletal / metabolism
  • Muscle, Skeletal / metabolism*
  • Sarcolemma / metabolism
  • Sarcomeres / metabolism
  • Vacuoles / metabolism
  • Young Adult

Substances

  • Calcium