ISSN:
1573-2657
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Medicine
Notes:
Abstract The canine latissimus dorsi was stimulated at 1 Hz via the thoracodorsal nerve for 70 days. Seven days of muscle stimulation caused muscle mass, fibre cross-sectional areas, and tetanic tensions to decrease. Fourteen days of stimulation produced marked decreasesin Ca2+-uptake rates in a membrane fraction containing sarcoplasmic reticulum. At this time there was a decline infusion frequency, but no statistically significant changes in time-to-peak tension, total contraction times, or half-relaxation times. With 42 days of stimulation a switch from the fast-twitch to the slow-twitch phenotype was indicated by elevations in the levels of expression of the slow-twitch isoform of sarco(endo)plasmic reticulum Ca2+-ATPase and myosin heavy chain-I, and increases in half-relaxation times, total contraction times and time-to-peak tensions. Decreases in muscle shortening velocity correlated negatively with increases in myosin heavy chain-I levels. Up-regulation of the slow-twitch isoform of sarco(endo)plasmic reticulum Ca2+-ATPase protein positively correlated with increases in half-relaxation times. The changes in the slow-twitch isoform of sarco(endo)plasmic reticulum Ca2+-ATPase and myosin heavy chain-I levels indicated coordinate expression of these two proteins in chronically stimulated muscles
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1018685001214
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