title: Roles of sigma receptors in isolated guinea pig parietal cells.
abstract: Sigma receptor involvement in the oxyntic mechanism of gastric parietal cells was investigated using isolated guinea pig parietal cells. Using the 14C-aminopyrine accumulation method, di(orthotolyl)guanidine (DTG), a sigma receptor agonist, demonstrated peak stimulation of acid production at a concentration of 5 x 10(-5) M. The DTG-induced stimulatory effect on 14C-aminopyrine accumulation in preparations enriched in parietal cells was inhibited by haloperidol, a DTG inhibitor, and omeprazole, a proton pump inhibitor, in a concentration-dependent manner. Assessment of the interaction between DTG and agonists for histamine, gastrin, and muscarine receptors demonstrated a potentiating interaction effect on acid production only when parietal cells were exposed to both DTG and histamine. A receptor-binding assay using 3H-DTG revealed two sigma receptor subtypes, sigma 1 and sigma 2, on the crude membranes of parietal cells. There was a direct relationship between DTG dose and intracellular Ca2+ concentration, but there was no change in intracellular cyclic adenosine 5'-monophosphate (cAMP) concentration when parietal cells were exposed to DTG. These results demonstrate that sigma receptors exist on guinea pig gastric parietal cells and suggest that they play a role in acid production via an increase in intracellular Ca2+ concentration.
authors.affiliation: 6th Department of Internal Medicine, School of Medicine, Tokai University, Kanagawa, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Suzuki
authors.forename: N
authors.initials: N
authors.lastname: Tani
authors.forename: N
authors.initials: N
authors.lastname: Mutoh
authors.forename: T
authors.initials: T
authors.lastname: Miwa
mesh_terms: D000632:Aminopyrine / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002250:Carbon Radioisotopes; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D006146:Guanidines / Q000494:pharmacology; D006168:Guinea Pigs; D007553:Isotope Labeling; D008297:Male; D010295:Parietal Cells, Gastric / Q000187:drug effects / Q000502:physiology*; D017480:Receptors, sigma / Q000819:agonists / Q000502:physiology*; D014316:Tritium
chemical_list: D002250:Carbon Radioisotopes; D006146:Guanidines; D017480:Receptors, sigma; D000632:Aminopyrine; D014316:Tritium; D000242:Cyclic AMP; C050232:1,3-ditolylguanidine; D002118:Calcium