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Histamine is an antagonist of the acetylcholine receptor at the frog endplate
Author(s) -
Ariyoshi M.,
Hasuo H.,
Koketsu K.,
Ohta Y.,
Tokimasa T.
Publication year - 1985
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.1476-5381.1985.tb08832.x
Subject(s) - histamine , acetylcholine , chemistry , acetylcholine receptor , biophysics , cholinergic , nicotinic agonist , histamine h1 receptor , neuromuscular transmission , medicine , endocrinology , antagonist , biology , receptor , biochemistry
1 The effects of histamine on the acetylcholine (ACh) receptor‐channel complex were examined by means of voltage‐clamp at the frog endplate. ACh was ionophoretically applied to the endplate. Histamine was added to the perfusate. 2 Histamine (100 nM − 1 mM) reversibly depressed the peak amplitude of the ACh‐induced inward current in a dose‐dependent manner. 3 The double reciprocal plot of the dose‐response relationship between the peak ACh current and the amount of ACh applied suggested that histamine (100 μM) depressed the ACh‐induced current in a competitive manner. 4 Histamine prevented the specific ACh binding site within the receptor‐channel complex from binding erabutoxin, a sea‐snake venom, which binds irreversibly to the specific ACh binding site. 5 Histamine had no detectable effects on the equilibrium potential of the endplate current but shortened the half‐decay time of the endplate current in a voltage‐dependent manner. 6 It was therefore concluded that histamine blocks not only the specific ACh binding site but also interacts with the ACh‐channel site. 7 The present experiments strongly suggest that histamine can act as an antagonist to modulate nicotinic cholinergic transmission.