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Intracellular Ca2+ transients in mouse soleus muscle after hindlimb unloading and reloadingThe objective of this study was to determine whether altered intracellular Ca(2+) handling contributes to the specific force loss in the soleus muscle after unloading and/or subsequent reloading of mouse hindlimbs. Three groups of female ICR mice were studied: 1) unloaded mice (n = 11) that were hindlimb suspended for 14 days, 2) reloaded mice (n = 10) that were returned to their cages for 1 day after 14 days of hindlimb suspension, and 3) control mice (n = 10) that had normal cage activity. Maximum isometric tetanic force (P(o)) was determined in the soleus muscle from the left hindlimb, and resting free cytosolic Ca(2+) concentration ([Ca(2+)](i)), tetanic [Ca(2+)](i), and 4-chloro-m-cresol-induced [Ca(2+)](i) were measured in the contralateral soleus muscle by confocal laser scanning microscopy. Unloading and reloading increased resting [Ca(2+)](i) above control by 36% and 24%, respectively. Although unloading reduced P(o) and specific force by 58% and 24%, respectively, compared with control mice, there was no difference in tetanic [Ca(2+)](i). P(o), specific force, and tetanic [Ca(2+)](i) were reduced by 58%, 23%, and 23%, respectively, in the reloaded animals compared with control mice; however, tetanic [Ca(2+)](i) was not different between unloaded and reloaded mice. These data indicate that although hindlimb suspension results in disturbed intracellular Ca(2+) homeostasis, changes in tetanic [Ca(2+)](i) do not contribute to force deficits. Compared with unloading, 24 h of physiological reloading in the mouse do not result in further changes in maximal strength or tetanic [Ca(2+)](i).
Document ID
20040141897
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Ingalls, C. P.
(College Station Texas 77843-4243, United States)
Warren, G. L.
Armstrong, R. B.
Hamilton, S. L.
Date Acquired
August 22, 2013
Publication Date
July 1, 1999
Publication Information
Publication: Journal of applied physiology (Bethesda, Md. : 1985)
Volume: 87
Issue: 1
ISSN: 8750-7587
Subject Category
Aerospace Medicine
Distribution Limits
Public
Copyright
Other
Keywords
NASA Program Biomedical Research and Countermeasures
Non-NASA Center
NASA Discipline Musculoskeletal

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