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Imidazoline Recognition Sites and Stomach Function a
Author(s) -
MOLDERINGS G. J.,
BURIAN M.,
MENZEL S.,
DONECKER K.,
HOMANN J.,
NILIUS M.,
GÖTHERT M.
Publication year - 1999
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.1999.tb09377.x
Subject(s) - agmatine , imidazoline receptor , chemistry , idazoxan , binding site , stomach , ligand (biochemistry) , biochemistry , receptor , endocrinology , biology , antagonist , amino acid , prazosin , arginine
Radioligand binding experiments carried out in cell membranes from rat and human stomach revealed the existence of non‐adrenoceptor [ 3 H]clonidine and [ 3 H]idazoxan binding sites and of [ 3 H]DTG (1,2‐di‐(2‐tolyl)guanidine) binding sites. In rat stomach, specific binding was inhibited by imidazolines and guanidines and by non‐imidazoline σ‐site ligands, respectively, at different rank orders of affinity, suggesting the existence of non‐I 1 /non‐I 2 [ 3 H]clonidine binding sites, I 2 ‐imidazoline binding sites as well as σ 2 ‐like‐sites. These sites are not directly related to a postsynaptic contractile effect on rat gastric smooth muscle or to acid release from isolated gastric glands. Finally, we demonstrated that the gastric pathogen Helicobacter pylori is able to form and to release the endogenous imidazoline receptor ligand agmatine and that considerable amounts of agmatine are present in human gastric juice. The quantities of agmatine were higher in gastric juice from H. pylori ‐positive than H. pylori ‐negative patients.