Childers MK, Okamura CS, Bogan DJ, Bogan JR, Petroski GF, McDonald K, Kornegay JN. Eccentric contraction injury in dystrophic canine muscle.
Arch Phys Med Rehabil 2002;
83:1572-8. [PMID:
12422328 DOI:
10.1053/apmr.2002.35109]
[Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
OBJECTIVE
To test the hypothesis that eccentric contractions induce greater injury in dystrophic compared with normal canine muscle.
DESIGN
Blinded cohort study.
SETTING
Animal laboratory.
ANIMALS
Ten dogs with a homologue to Duchenne muscular dystrophy (Golden retriever muscular dystrophy [GRMD]) and 10 normal littermates.
INTERVENTIONS
Contractions induced in tibiotarsal flexors and extensors by sciatic nerve stimulation. Because more powerful extensors overrode flexors, eccentric contractions occurred in flexors. Concentric contractions were induced in contralateral flexors by peroneal nerve stimulation.
MAIN OUTCOME MEASURE
Tibiotarsal flexion force 3 days after contractions. Muscle was examined for injury (esterase activity, Evans blue dye penetration) and regeneration (embryonic myosin isoform expression).
RESULTS
Mean force deficit after eccentric flexor contractions was 43.3%+/-25.7% in GRMD dogs compared with 25.0%+/-18.4% in controls (P=.04, Wilcoxon rank-sum test). Concentric contractions induced force deficits in GRMD but not normal dogs; however, the difference between the 2 groups was not significant (P=.08, Wilcoxon rank-sum test). After concentric contractions in controls, force decrements correlated with esterase activity measured by area (r=.794, P=.006) and intensity (r=.697, P=.025, Spearman rank correlation). No other significant correlation was detected between force and biopsy data.
CONCLUSIONS
Force data support the hypothesis that eccentric contractions induce greater injury in dystrophic compared with normal canine muscle. Phenotypic features of the dystrophic canine model used here are similar to those of humans with Duchenne's.
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