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THE MODE OF ACTION OF NEOSTIGMINE AND PHYSOSTIGMINE ON THE GUINEA‐PIG TRACHEALIS MUSCLE
Author(s) -
CARLYLE R. F.
Publication year - 1963
Publication title -
british journal of pharmacology and chemotherapy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0366-0826
DOI - 10.1111/j.1476-5381.1963.tb01509.x
Subject(s) - physostigmine , neostigmine , trachealis muscle , acetylcholine , atropine , chemistry , free nerve ending , guinea pig , cholinesterase , cholinergic , pharmacology , anesthesia , endocrinology , medicine , biochemistry , charybdotoxin , membrane potential
Neostigmine (2.2 μg/ml.) or physostigmine (3.3 μg/ml.) contracted guinea‐pig isolated tracheal chains. The anticholinesterase diisopropylphosphodiamidic fluoride (mipafox) itself caused no contractile response even in concentrations of 100 μg/ml., yet neostigmine or physostigmine still caused contractions after treatment with mipafox. The responses were abolished by hyoscine or atropine. Local anaesthetics, cooling, ionic changes and hemicholinium, all known to inhibit the release of acetylcholine from nerve endings, abolished or much reduced the responses. It seems that the contractile response to physostigmine or neostigmine does not depend on their anticholinesterase activity, but on their ability to release acetylcholine from postganglionic parasympathetic nerve endings.