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Drug‐induced myotonia in human intercostal muscle
Author(s) -
Kwiecińaski Hubert,
LehmannHorn Frank,
Rüdel Reinhardt
Publication year - 1988
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.880110609
Subject(s) - chemistry , myotonia , myotonia congenita , contraction (grammar) , potassium channel , potassium , medicine , pharmacology , endocrinology , anesthesia , biophysics , biology , organic chemistry , myotonic dystrophy
The myotonia‐inducing effects of furosemide and clofibrate, two widely used pharmaceutical agents, were investigated in excised human external intercostal muscle. The effects of anthracene‐9‐carboxylic acid (9‐AC), a well‐known myotonia‐producing chemical, were also tested for comparison. In the presence of these drugs the electrical threshold was lowered, and a constant current pulse produced multiple spiking. Short trains of direct stimuli were often followed by after‐activity, and this caused a myotonia‐like prolongation of muscle contraction. Voltage‐clamp experiments showed that 0.05 m M anthracene‐9‐carboxylic acid, 1 m M furosemide, and 1 m M clofibrate decreased the chloride conductance of the muscle fiber membrane to 14, 18, and 40%, respectively, of the normal value, and the myotonia‐inducing potency of the 3 drugs was correlated with the decreased chloride conductance. The potassium currents were not affected by these compounds.