Gastrin receptors on nonparietal cells isolated from canine fundic mucosa.
The cellular localization of gastrin receptors was studied using dispersed canine fundic mucosal cells. In previous studies 125I-[Leu15]gastrin-17 (125I-[Leu15]G-17) binding was found to parietal cells, but gastrin binding was also found in the small-cell elutriator fractions (SCEF). In the present study a density gradient was used to further separate the SCEF and the distribution of 125I-[Leu15]G-17 binding correlated with cellular content of somatostatinlike immunoreactivity (SLI). In contrast, 125I-[Leu15]G-17 binding was inversely correlated with the histamine content of the fractions. 125I-[Leu15]G-17 binding to the SCEF was rapid and reversible. Total binding was 0.29 +/- 0.02 fmol/10(6) cells (mean +/- SE, n = 15); excess unlabeled G-17 inhibited 85% of this binding. G-17, [Leu15]G-17, and 127I-[Leu15]G-17 were equipotent in inhibiting 125I-[Leu15]G-17 binding and stimulating SLI secretion from the SCEF placed in short-term culture, whereas 127I-G-17 had a low potency for both effects. Proglumide, known to inhibit cholecystokinin binding to pancreatic acinar cell receptors, also inhibited 125I-[Leu15]G-17 binding to the SCEF and inhibited G-17 stimulated SLI release. We conclude that in the canine fundic mucosa gastrin interacts with receptor sites on parietal cells and somatostatin cells but probably not on fundic mucosal histamine-containing cells. These receptor sites for gastrin may activate counterbalancing mechanisms regulating the secretion of acid.
D000818:Animals; D002469:Cell Separation; D002499:Centrifugation, Density Gradient; D004285:Dogs; D005748:Gastric Fundus; D005753:Gastric Mucosa / Q000166:cytology / Q000378:metabolism*; D005755:Gastrins / Q000378:metabolism; D006706:Homeostasis; D011956:Receptors, Cell Surface / Q000378:metabolism*; D011949:Receptors, Cholecystokinin; D013223:Statistics as Topic; D013997:Time Factors
D005755:Gastrins; D011956:Receptors, Cell Surface; D011949:Receptors, Cholecystokinin; C013550:gastrin 17