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Tetanus toxin reduces local and descending regulation of the H‐reflex
Author(s) -
Matthews Christopher C.,
Fishman Paul S.,
Wittenberg George F.
Publication year - 2014
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.23938
Subject(s) - tetanus , toxin , reflex , medicine , neuroscience , anesthesia , immunology , biology , microbiology and biotechnology , vaccination
: Skeletal muscles that are under the influence of tetanus toxin show an exaggerated reflex response to stretch. We examined which changes in the stretch reflex may underlie the exaggerated response. Methods : H‐reflexes were obtained from the tibialis anterior (TA) and flexor digitorum brevis (FDB) muscles in rats 7 days after intramuscular injection of tetanus toxin into the TA. Results : We found effects of the toxin on the threshold, amplitude, and duration of H‐waves from the TA. The toxin inhibited rate‐dependent depression in the FDB between the stimulation frequencies of 0.5–50 HZ and when a conditioning magnetic stimulus applied to the brain preceded a test electrical stimulus delivered to the plantar nerve. Conclusions : Tetanus toxin increased the amplitude of the H‐wave and reduced the normal depression of H‐wave amplitude that is associated with closely timed stimuli, two phenomena that could contribute to hyperactivity of the stretch reflex. Muscle Nerve 49:495–501, 2014