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Contractile and EMG studies of murine myotonia ( mto ) and muscular dystrophy ( dy/dy )
Author(s) -
Entrikin Richard K.,
Abresch Richard T.,
Sharman Robert B.,
Larson Douglas B.,
Levine Neil A.
Publication year - 1987
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.880100403
Subject(s) - myotonia , myotonic dystrophy , isometric exercise , muscular dystrophy , contractility , chemistry , neuromuscular junction , anatomy , medicine , endocrinology , neuroscience , biology
This report focuses on the myotonic ( mto ) mouse, an autosomal recessive neuromuscular mutant first described in 1982. Studies in vivo confirmed the presence of hindlimb rigidity during walking and typical myotonic electromyographic (EMG) discharges that persisted after nerve transection and complete neuromuscular blockade. Studies of the contractility of mto muscles in vitro revealed reduced peak isometric tetanic tension and greatly prolonged relaxation times. Tubocurarine did not affect tension parameters, but did antagonize the delayed relaxation in vitro. On the basis of EMG studies alone this mutant can accurately be described as myotonic. Reduction of the contractile abnormalities by tubocurarine in vitro, however, poses further questions regarding the nature of the disorder. Although the more familiar dystrophic mouse ( dy/dy ) has been termed “myotonic” by some, the new mto mutant differs from it in all aspects examined.