Key result
Continuous stimulation of fast rat muscles at 10 or 20 Hz for 55-61 days reduced maximum shortening velocity by 50% and increased type 1 fibers from 4% to 34%.
Why the study?
Does continuous electrical stimulation induce fast-to-slow transformation in rat skeletal muscle?
Does continuous electrical stimulation induce fast-to-slow transformation in rat skeletal muscle?
Continuous electrical stimulation induces fast-to-slow transformation in rat skeletal muscle, demonstrating that activity-dependent gene expression mechanisms are not exclusive to larger mammals.
Answers are grounded in this paper and cite their sources.
Chronic stimulation transforms rat fast muscle fibers; leaves open translation to human neuromuscular therapies.
Several previous studies have failed to demonstrate changes due to chronic stimulation in contractile speed of innervated fast rat muscles, and it has been suggested that the adaptive capacity of skeletal muscle in this species is limited. We have reassessed this contention. Fast muscles of the rat hind limb were stimulated continuously at 10 or 20 Hz for 55-61 days. The maximum shortening velocity of the extensor digitorum longus muscles was reduced to 50% of the control value. The proportion of type 1 fibers increased from 4% in control muscle to 34% in stimulated muscles and there was a corresponding reduction in type 2B/D fibers. The proportion of type 2A fibers after stimulation was similar to that in control muscles. These results, taken together with our published analyses of myosin isoform composition of these muscles, show that the mechanisms that control gene expression in response to activity are not exclusive to larger mammals.
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Jarvis et al. (1996) studied this question. Continuous stimulation vs. Control muscle was evaluated on Proportion of type 1 fibers. Continuous stimulation of fast rat muscles at 10 or 20 Hz for 55-61 days reduced maximum shortening velocity by 50% and increased type 1 fibers from 4% to 34%.
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