Skip Navigation

This Article
Right arrow Full Text (PDF)
Right arrow E-Letters: Submit a response to the article
Right arrow Alert me when this article is cited
Right arrow Alert me when E-letters are posted
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrowRequest Permissions
Right arrow Disclaimer
Google Scholar
Right arrow Articles by JONES, S. V. P.
Right arrow Articles by MARSHALL, I. G.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by JONES, S. V. P.
Right arrow Articles by MARSHALL, I. G.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

British Journal of Anaesthesia, 1987, Vol. 59, No. 6 776-783
© 1987 The Board of Management and Trustees of the British Journal of Anaesthesia

other

NON-COMPETITIVE EFFECTS OF DISOPYRAMIDE AT THE NEUROMUSCULAR JUNCTION: EVIDENCE FOR ENDPLATE ION CHANNEL BLOCK

S. V. P. JONES, PH.D.* and I. G. MARSHALL, PH.D.

Department of Physiology and Pharmacology, University of Strathclyde Glasgow Gl 1XW

*Present address: Laboratory of Neurophysiology, NINCDS, National Institutes of Health, Bethesda, MD 20205, U.S.A.

The effects of disopyramide were studied at the neuromuscular junction in an attempt to elucidate the mechanism of its blocking action at this site. Disopyramide 5 x 10–5-10–3 mol litre–1 produced a concentration-dependent reduction of twitch amplitude in the indirectly stimulated chick biventer cervicis preparation, but greater concentrations were required to reduce twitches elicited directly in the presence of erabutoxin-b 1µg ml–1. Equieffective twitch blocking doses of either disopyramide or tubocurarine greatly reduced agonist responses to acetylcholine and carbachol, but the reduction was less for magnesium-blocked twitches. Neostigmine antagonized tubocurarine-induced, but not diso-pyramide-induced, blockade of twitches. Concentration-response profiles to acetylcholine and carbachol were shifted to the right in a non-parallel fashion and the maximal response was depressed by disopyramide 5 x 10–5-5 x 10–4 mol litre–1. Intracellular recording studies carried out in the cut, voltage-clamped costo-cutaneous muscle of the garter snake showed that disopyramide 5 x 10–5-5 x 10–4 mol litre–1 produced a concentration- and voltage-dependent reduction of the amplitude of neurally evoked endplate-currents (EPC) and of the time constant of decay ({tau}) of EPC. We conclude that disopyramide possesses a non-competitive blocking action at the neuromuscular junction, which is not reversible by anticholinesterase agents. The voltage-dependent nature of the block suggests that it is mediated via blockade of the open form of the acetylcholine-activated receptor-ion channel complex.


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.