Premium
The determination of receptor constants for histamine H 2 ‐agonists in the guinea‐pig isolated right atrium using an irreversible H 2 ‐antagonist
Author(s) -
Rising T. J.,
Steward A.
Publication year - 1986
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.1476-5381.1986.tb10173.x
Subject(s) - dimaprit , histamine , chemistry , dissociation constant , agonist , histamine h2 receptor , guinea pig , competitive antagonist , pharmacology , antagonist , receptor , medicine , endocrinology , biology , biochemistry
1 From measurements of chronotropy in the guinea‐pig isolated right atrium, a compound (E1309) was found which behaved as an irreversible antagonist at the histamine H 2 receptor. 2 E1309 was used to block irreversibly a proportion of the H 2 receptors and the dissociation constants, relative efficacies and receptor reserves of four H 2 ‐agonists were determined. 3 The calculated dissociation constants were similar to the K i values reported from H 2 ‐radioligand binding studies but different from the observed EC 50 values. 4 The order of potency for the four H 2 ‐agonists was impromidine > > histamine > dimaprit> 4‐methylhistamine. 5 The order of relative efficacy was 4‐methylhistamine > dimaprit > histamine > impromidine, the natural agonist not being the most efficacious. This atypical finding is discussed in relation to other receptor classes.