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Muscle function in a patient with Brody's disease
Author(s) -
De Ruiter Cornelis J.,
Wevers Ron A.,
Van Engelen Baziel G.M.,
Verdijk Peter W.L.,
De Haan Arnold
Publication year - 1999
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/(sici)1097-4598(199906)22:6<704::aid-mus6>3.0.co;2-z
Subject(s) - adductor pollicis muscle , medicine , muscle contraction , muscle relaxation , contraction (grammar) , endocrinology , relaxation (psychology) , muscle fatigue , skeletal muscle , ulnar nerve , chemistry , electromyography , anatomy , physical medicine and rehabilitation , elbow
Adductor pollicis muscle function of a 21‐year‐old man with genetically confirmed Brody's disease (sarcoplasmic reticulum [SR] ‐Ca 2+ ATPase deficiency) was investigated to study the possible effects of reduced SR‐Ca 2+ ATPase activity on muscle relaxation and force production. Following maximal electrical activation of the ulnar nerve, tetanic muscle half‐relaxation time was greater in the patient (246 ± 10 ms) than control subjects (97 ± 4 ms, n = 8). During repetitive activation, there was a similar decline in maximal shortening velocity in the patient and controls, indicating a comparable reduction in cross‐bridge cycling rate. The finding that the slowing of relaxation was greater in the patient (329 ms versus 138 ± 20 ms) suggests that there was a further reduction of SR‐Ca 2+ ATPase activity in the patient's muscle during fatigue. Following a voluntary contraction, involuntary activity of the antagonist muscles facilitated force decline and masked the impaired relaxation in the patient. This antagonist‐induced relaxation indicates that it might be difficult to establish impaired muscle relaxation with voluntary contractions. © 1999 John Wiley & Sons, Inc. Muscle Nerve 22: 704–711, 1999.