O'Connell, Kathleen and Gannon, Joan and Doran, Philip and Ohlendieck, Kay (2008) Reduced expression of sarcalumenin and related Ca2+-regulatory proteins in aged rat skeletal muscle. Experimental Gerontology, 43 (10). pp. 958-961. ISSN 0531-5565

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Abstract

In skeletal muscle, Ca(2+)-cycling through the sarcoplasm regulates the excitation-contraction-relaxation cycle. Since uncoupling between sarcolemmal excitation and fibre contraction may play a key role in the functional decline of aged muscle, this study has evaluated the expression levels of key Ca(2+)-handling proteins in senescent preparations using immunoblotting and confocal microscopy. Sarcalumenin, a major luminal Ca(2+)-binding protein that mediates ion shuttling in the longitudinal sarcoplasmic reticulum, was found to be greatly reduced in aged rat tibialis anterior, gastrocnemius and soleus muscle as compared to adult specimens. Minor sarcolemmal components of Ca(2+)-extrusion, such as the surface Ca(2+)-ATPase and the Na(+)-Ca(2+)-exchanger, were also diminished in senescent fibres. No major changes were observed for calsequestrin, sarcoplasmic reticulum Ca(2+)-ATPase and the ryanodine receptor Ca(2+)-release channel. In contrast, the age-dependent reduction in the alpha(1S)-subunit of the dihydropryridine receptor was confirmed. Hence, this report has shown that downstream from the well-established defect in coupling between the t-tubular voltage sensor and the junctional Ca(2+)-release channel complex, additional age-related alterations exist in the expression of essential Ca(2+)-handling proteins. This may trigger abnormal luminal Ca(2+)-buffering and/or decreased plasmalemmal Ca(2+)-removal, which could exacerbate impaired signaling or disturbed intracellular ion balance in aged fibres, thereby causing contractile weakness.

Item Type:	Article
Keywords:	Aging; Ca2+-ATPase; Ca2+-binding protein; Excitation–contraction uncoupling; Na+–Ca2+-exchanger; Sarcalumenin; Sarcopenia;
Academic Unit:	Faculty of Science and Engineering > Biology
Item ID:	7498
Identification Number:	https://doi.org/10.1016/j.exger.2008.07.006
Depositing User:	Prof. Kay Ohlendieck
Date Deposited:	11 Oct 2016 15:33
Journal or Publication Title:	Experimental Gerontology
Publisher:	Elsevier
Refereed:	Yes
URI:	http://www.sciencedirect.com
Use Licence:	This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

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