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E-C Coupling and Contractile Characteristics of Mechanically Skinned Single Fibres from Young Rats During Rapid Growth and Maturation

Goodman, Craig and Blazev, Ronnie and Kemp, Justin and Stephenson, Gabriela (2008) E-C Coupling and Contractile Characteristics of Mechanically Skinned Single Fibres from Young Rats During Rapid Growth and Maturation. Pflugers Archiv-European Journal of Physiology, 456 (6). pp. 1217-1228. ISSN 0031-6768

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Abstract

The postnatal growth of rats involves a developmental phase (0 to ∼3 weeks), a rapid growth phase (∼3 to ∼10 weeks), and a slower maturation phase (∼10 weeks+). In this study, we investigated the age-related changes in excitation–contraction (E–C) coupling characteristics of mammalian skeletal muscle, during rapid growth (4– 10 weeks) and maturation (10–21 weeks) phases, using single, mechanically skinned fibres from rat extensor digitorum longus (EDL) muscle. Fibres from rats aged 4 and 8 weeks produced lower maximum T-system depolarizationinduced force responses and fewer T-system depolarizationinduced force responses to 75% run-down than those produced by fibres from rats aged 10 weeks and older. The sensitivity of the contractile apparatus to Ca2+ in fibres from 4-week rats was significantly higher than that in fibres from 10-week rats; however, the maximum Ca2+-activated force per skinned fibre cross-sectional area (specific force) developed by fibres from 4-week rats was on average ∼44% lower than the values obtained for all the other age groups. In agreement with the age difference in specific force, the MHC content of EDL muscles from 4-week rats was ∼29% lower than that of 10-week rats. Thus, mechanically skinned fibres from rats undergoing rapid growth are less responsive to T-system depolarization and maximal Ca2+ activation than fibres from rats at the later stage of maturation or adult rats. These results suggest that during the rapid growth phase in rats, the structure and function of elements involved in E–C coupling in fast-twitch skeletal muscle continue to undergo significant changes.

Item Type: Article
Uncontrolled Keywords: ResPubID14988, excitation–contraction coupling, skinned fibre, muscle development, skeletal muscle fibre, muscle contraction, muscle fatigue, specific force
Subjects: Faculty/School/Research Centre/Department > School of Biomedical and Health Sciences
FOR Classification > 0606 Physiology
SEO Classification > 970106 Expanding Knowledge in the Biological Sciences
Faculty/School/Research Centre/Department > Centre for Ageing, Rehabilitation, Exercise & Sport Science (CARES)
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Depositing User: VUIR
Date Deposited: 29 Sep 2011 04:11
Last Modified: 19 Jul 2016 05:31
URI: http://vuir.vu.edu.au/id/eprint/3676
DOI: 10.1007/s00424-008-0474-9
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Citations in Scopus: 3 - View on Scopus

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