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CONTRACTURES ELICITED BY TETRAETHYLAMMONIUM IN AVIAN MUSCLE TREATED WITH METHOHEXITONE
Author(s) -
ELLIOTT R.C.
Publication year - 1979
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1979.tb10843.x
Subject(s) - muscle contracture , tetraethylammonium , medicine , anatomy , anesthesia , chemistry , potassium , organic chemistry
1 The chick biventer cervicis muscle immersed in methohexitone (8.8 × 10 −5 m ) responded to tetraethylammonium with contractures which were dose‐related. The ED 50 for tetraethylammonium was 2.1 × 10 −3 m . 2 In the absence of methohexitone, tetraethylammonium produced contractures only at much higher concentrations; these contractures were accompanied by fasciculations and neuromuscular block of the twitch fibres. 3 The contractures produced by tetraethylammonium in the presence of methohexitone were not reduced by exposure to botulinum toxin which eliminated all response of the muscle to indirect stimulation. 4 Tubocurarine (1.2 × 10 −6 m ) displaced the dose‐response curve for tetraethylammonium‐methohexitone‐induced contractures to the right. The dose‐ratio was 15.63 ± 1.98. 5 Physostigmine (1.8 × 10 −6 m ) potentiated the activity of tetraethylammonium‐methohexitone 3.26 or 3.84 fold, depending on the method of calculation used. 6 Physostigmine potentiated contractures elicited by indirect repetitive stimulation 4.8 to 6.0 fold more than it potentiated contractures due to tetraethylammonium‐methohexitone. 7 It is concluded that in the presence of methohexitone, tetraethylammonium produces contractures of the chick muscle by releasing acetylcholine but also by a direct agonist action on the cholinoceptor.