Electromechanical Stimulation Ameliorates Inactivity-induced Adaptations in the Medial Gastrocnemius of Adult Rats.
From: Brain Research Institute, University of California, Los Angeles, Los Angeles, CA 90095-1761, USA
Journal of applied physiology (Bethesda, Md. : 1985)
- Publish Date: Jul 2007
- ISSN: 8750-7587
- Volume: 103
- Issue: 1
- Pages: 195-205
- Medium: Print
- Language: English
- Citation (JAMA): Kim Soo J, Roy Roland R, Zhong Hui, et al. Electromechanical Stimulation Ameliorates Inactivity-induced Adaptations in the Medial Gastrocnemius of Adult Rats.. J. Appl. Physiol. Jul 2007;103:195-205
Abstract
The efficacy of high-load, short-duration isometric contractions, delivered as one vs. two sessions per day, on blunting inactivity-induced adaptations in the medial gastrocnemius (MG) were compared. Adult rats were assigned to a control (Con) or spinal cord-isolated (SI) group where one limb was stimulated (SI-Stim) while the other served as a SI control (SI-C). One bout of stimulation (BION microstimulator) consisted of a 100-Hz, 1-s stimulus, delivered every 30 s for 5 min with a 5-min rest period. This bout was repeated six times consecutively (SI-Stim1) or with a 9-h rest interval after the third bout (SI-Stim2) for 30 consecutive days. MG weights (relative to body weight) were 63, 72, and 79% of Con in SI-C, SI-Stim1, and SI-Stim2, respectively. Mean fiber size was 56% smaller in SI-C than in Con, and it was 19 and 31% larger in SI-Stim1 and SI-Stim2, respectively, compared with SI-C. Maximum tetanic tension was 42, 60, and 73% of Con in SI-C, SI-Stim1, and SI-Stim2, respectively. Specific tension was 77% of Con in SI-C, and at Con levels in both SI-Stim groups. SI increased the percent IIb myosin heavy chain composition (from 49 to 77%) and IIb+ fibers (from 63 to 79%): these adaptations were prevented by both Stim paradigms. These results demonstrate that 1) brief periods of high-load isometric contractions are effective in reducing inactivity-induced atrophy, functional deficits, and phenotypic adaptations in a fast hindlimb extensor, and 2) the same amount of stimulation distributed in two compared with one session per day is more effective in ameliorating inactivity-related adaptations.
Mesh Headings (Keywords): Adaptation, Physiological, Animals, Body Weight, Disease Models, Animal, Electric Stimulation Therapy, Female, Isometric Contraction, Muscle Fibers, Muscle Strength, Muscle, Skeletal, Muscular Atrophy, Myosin Heavy Chains, Organ Size, Phenotype, Protein Isoforms, Rats, Rats, Sprague-Dawley, Spinal Cord
Check for Full Text / PubMed Unique Identifier (PMID): 17431083
This abstract is part of PubMed, a service of the U.S. National Library of Medicine. PubMed includes more than 17 million citations from MEDLINE and other life science journals for biomedical articles. See Copyright and Disclaimers.
Linked medical terms appearing on this page are added by Healia to help readers find more information and are not part of the original PubMed document.
The data herein was last updated on July 8th, 2008 and may not reflect the most current and accurate data available from NLM.