Premium
The effects of agonists on the components of the cardiac muscarinic receptor
Author(s) -
Burgen A.S.V.
Publication year - 1987
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.1476-5381.1987.tb11327.x
Subject(s) - agonist , receptor , muscarinic acetylcholine receptor , population , endocrinology , chemistry , binding site , medicine , biology , stereochemistry , biophysics , biochemistry , environmental health
1 The binding of eleven agonists to muscarinic receptors in the rat heart has been measured in competition with [ 3 H]‐N‐methylscopolamine. 2 Full analysis of binding required the resolution of three components (SH, H and L). 3 The proportion of the H component was independent of agonist structure. The proportion of the SH component ranged from 2–36% of the total and was dependent on the agonist. The proportion of the L component varied in a complementary way from 59‐22% of the total. 4 The ratios of the affinities of ten of the agonists to the three components of the receptors were constant; the weakest binding agonist, choline, had lower ratios of affinity. 5 When saturated with guanylylimidodiphosphate (GppNHp) the SH receptor population was no longer detectable and the H receptor population was reduced by 63%: about 85% of the receptors was in the L population. 6 The affinity constants of agonists for the H and L forms of the receptors were not changed by GppNHp. 7 The results are interpreted in terms of the effects of accessory proteins on the proportions of binding and non‐binding conformations of the receptor.