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The correlation between electrical after‐activity and slowed relaxation in myotonia
Author(s) -
Iaizzo Paul A.,
LehmannHorn Frank
Publication year - 1990
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.880130311
Subject(s) - myotonia , relaxation (psychology) , muscle relaxation , fiber type , chemistry , muscle fibre , electromyography , positive correlation , anatomy , fiber , medicine , endocrinology , biophysics , biology , skeletal muscle , physical medicine and rehabilitation , organic chemistry , myotonic dystrophy
Abstract The correlation between electrical and mechanical after‐activity was studied in resealed fiber segments from patients with recessive generalized myotonia (Becker) and in intact fibers from normal muscles which were bathed in 9‐anthracene carboxylic acid. The tests were performed in vitro on small bundles of 100 fibers or less. Electromyographic activity and contractile force were measured simultaneously. The relaxation of rested‐state twitches and tetani was slowed and accompanied by after‐activity in both types of preparations. Often random activity was recorded. In all cases, the contractile force was highly correlated with the electromyographic signs of myotonia. These observations support the hypothesis that electrical afteractivity is fully responsible for the slowed relaxation in recessive generalized myotonia.