title: Fiber type-related changes in rat skeletal muscle calcium homeostasis during aging and restoration by growth hormone.
abstract: The mechanisms by which aging induces muscle impairment are not well understood yet. We studied the impact of aging on Ca2+ homeostasis in the slow-twitch soleus and the fast-twitch extensor digitorum longus (EDL) muscles of aged rats by using the fura-2 fluorescent probe. In both muscles aging increases the resting cytosolic calcium concentration ([Ca2+]i). This effect was independent on calcium influx since a reduced resting permeability of sarcolemma to divalent cations was observed in aged muscles likely due to a reduced activity of leak channels. Importantly the effects of aging on resting [Ca2+]i, fiber diameter, mechanical threshold and sarcolemmal resting conductances were less pronounced in the soleus muscle, suggesting that muscle impairment may be less dependent on [Ca2+]i in the slow-twitch muscle. The treatment of aged rats with growth hormone restored the resting [Ca2+]i toward adult values in both muscles. Thus, an increase of resting [Ca2+]i may contribute to muscle weakness associated with aging and may be considered for developing new therapeutic strategies in the elderly.
authors.affiliation: Division of Pharmacology, Department of Pharmaco-Biology, Faculty of Pharmacy, University of Bari, Bari I-70125, Italy.
authors.forename: Bodvael
authors.initials: B
authors.lastname: Fraysse
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Desaphy
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Rolland
authors.forename: Sabata
authors.initials: S
authors.lastname: Pierno
authors.forename: Antonella
authors.initials: A
authors.lastname: Liantonio
authors.forename: Viviana
authors.initials: V
authors.lastname: Giannuzzi
authors.forename: Claudia
authors.initials: C
authors.lastname: Camerino
authors.forename: M Paola
authors.initials: MP
authors.lastname: Didonna
authors.forename: Daniela
authors.initials: D
authors.lastname: Cocchi
authors.forename: Annamaria
authors.initials: A
authors.lastname: De Luca
authors.forename: Diana
authors.initials: D
authors.lastname: Conte Camerino
mesh_terms: D000375:Aging; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D016257:Fura-2 / Q000378:metabolism; D013006:Growth Hormone / Q000494:pharmacology*; D006706:Homeostasis / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D010539:Permeability; D051381:Rats; D017208:Rats, Wistar; D012508:Sarcolemma / Q000378:metabolism
chemical_list: D013006:Growth Hormone; D002118:Calcium; D016257:Fura-2