title: Human skeletal muscle plasmalemma alters its structure to change its Ca2+-handling following heavy-load resistance exercise.
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+]cytoto help maintain fibre viability during the period associated with delayed onset muscle soreness.
authors.affiliation: School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia.
authors.forename: Tanya R
authors.initials: TR
authors.lastname: Cully
authors.affiliation: Department of Biochemistry &Genetics, La Trobe Institute for Molecular Science, La Trobe University, Melbourne, Victoria 3086, Australia.
authors.forename: Robyn M
authors.identifier: 0000-0003-3697-589X
authors.initials: RM
authors.lastname: Murphy
authors.affiliation: School of Human Movement and Nutritional Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia.|Centre of Excellence for Applied Sport Science Research, Queensland Academy of Sport, Brisbane, Queensland 4111, Australia.
authors.forename: Llion
authors.initials: L
authors.lastname: Roberts
authors.affiliation: Norwegian School of Sport Sciences, Oslo N-0806, Norway.
authors.forename: Truls
authors.initials: T
authors.lastname: Raastad
authors.affiliation: School of Human Movement and Nutritional Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Fassett
authors.affiliation: School of Human Movement and Nutritional Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia.
authors.forename: Jeff S
authors.initials: JS
authors.lastname: Coombes
authors.affiliation: School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia.|School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Izzy
authors.identifier: 0000-0003-2461-478X
authors.initials: I
authors.lastname: Jayasinghe
authors.affiliation: School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia.
authors.forename: Bradley S
authors.identifier: 0000-0003-0700-4867
authors.initials: BS
authors.lastname: Launikonis
mesh_terms: D000328:Adult; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D006801:Humans; D008297:Male; D018613:Microscopy, Confocal; D009119:Muscle Contraction / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism*; D012508:Sarcolemma / Q000378:metabolism; D012518:Sarcomeres / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism; D055815:Young Adult
chemical_list: D002118:Calcium