Magnitude of Injury to the Extensor Digitorum Longus Muscles Following Single Lengthening Contractions at Different Temperatures In Vitro and In Situ
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Authors
Dedhia, Manish M.
Issue Date
1991
Type
Thesis
Language
en_US
Keywords
Alternative Title
Abstract
Extensor digitorum longus (EDL) muscles from 17 male
CD-1 mice were studied at 25º C. Data collected in vitro at
25º c were compared with data previously collected at 35º c
by others. I tested the hypotheses that 1) the amount of
injury produced by single-lengthening contractions performed
in situ does not differ compared with contractions performed
in vitro, 2) following single-lengthening contractions, the
EDL muscles are injured to a lesser degree at 25 °c than at
35º C. The EDL muscles were injured in vitro by activating
the muscle to contract to 85% of maximum force and then
lengthened with isovelocity ramps. The muscles were
passively shortened 5% of fiber length (Lf) and then
lengthened to 50% and 75% of Lf at velocities of 0.5, 1.0,
2.0, and 3.0 Lf/second. The magnitude of injury was assessed
immediately afterward by the deficit-in-force compared to
the contralateral controls. The amount of power absorbed was
calculated by a computer. For the in vitro protocol, injury
to the EDL muscles was observed during both the 50% and 75%
length changes at each velocity. At 25º c, the magnitude of
injury to the EDL muscles after single-lengthening
contractions of 50% of Lf at 0.5 Lf/second, were similar for
the in situ and in vitro protocols. At different
temperatures, greater injury to EDL muscles was observed at
35 °C than at 25 °C. Although mechanical factors are likely
involved to the immediate injury to the fibers, the greater
injury at a higher temperature suggests chemical factors may
also be involved.
Description
v, 25 p.
Citation
Publisher
Kalamazoo College
License
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