Regulation of parietal cell calcium signaling in gastric glands

Abstract

The ligands interacting with enterochromaffin-like (ECL) and parietal cells and the signaling interactions between these cells were investigated in rabbit gastric glands using confocal microscopy. Intracellular calcium concentration ([Ca(2+)](i)) changes were used to monitor cellular responses. Histamine and carbachol increased [Ca(2+)](i) in parietal cells. Gastrin (1 nM) increased [Ca(2+)](i) in ECL cells and adjacent parietal cells. Only the increase of [Ca(2+)](i) in parietal cells was inhibited by H(2) receptor antagonists (H(2)RA). Gastrin (10 nM) evoked an H(2)RA-insensitive [Ca(2+)](i) increase in parietal cells. Carbachol produced large H(2)RA- and somatostatin-insensitive signals in parietal cells. Pituitary adenylate cyclase-activating peptide (PACAP, 100 nM) elevated [Ca(2+)](i) in ECL cells and adjacent parietal cells. H(2)RAs abolished the PACAP-stimulated [Ca(2+)](i) increase in adjacent parietal cells. Somatostatin did not inhibit the increase of [Ca(2+)](i) in parietal cells stimulated with histamine, high gastrin concentrations, or carbachol but abolished ECL cell calcium responses to gastrin or PACAP. Hence, rabbit parietal cells express histaminergic, muscarinic, and CCK-B receptors coupled to calcium signaling but insensitive to somatostatin, whereas rabbit and rat ECL cells express PACAP and CCK-B calcium coupled receptors sensitive to somatostatin.

Transcriptomes of purified gastric ECL and parietal cells: identification of a novel pathway regulating acid secretion

“…The latter gene is not represented as an oligonucleotide probe on our 22K rat gene expression microarray. CCKB/gastrin receptor expression has been found in a variety of other gastric mucosal cell types including PC (3,55), chief cells (63), and D cells (10,55). This ubiquitous presence is confirmed by the finding that the expression of the receptor mRNA in ECL cells is only 2.2 times higher compared with total fundic epithelium and actually is also slightly more expressed in PC-enriched fractions.…”

“…After the apelin is washed out (time point 4), rechallenge of the system with gastrin results in Ca 2ϩ signal only in the ECL cell at 1 nM concentration (time point 5). To show PC viability at the end of the experiment, 10 nM gastrin was used (time point 6) resulting in a simultaneous increase in intracellular Ca 2ϩ concentrations in both cells mediated by the high-affinity gastrin receptor on ECL cells and the low-affinity receptor on PC, as previously published (3).…”

Pituitary Adenylate Cyclase-Activating Polypeptide and Its Receptors: 20 Years after the Discovery

“…Because histamine is a potent stimulator of chloride secretion (Helander and Keeling, 1993), these data suggest that the effect of PACAP on gastric acid production can be accounted for, at least in part, by an indirect stimulation of ECL cells (Sandvik et al, 2001). In support of this hypothesis, PACAP elevates [Ca 2ϩ ] i in ECL cells and adjacent parietal cells in rabbit gastric glands, whereas histamine receptor antagonists abolish the Ca 2ϩ response in adjacent parietal cells (Athmann et al, 2000). PACAP also stimulates proliferation of gastric ECL cells through activation of the PKA, protein tyrosine kinase, and MAPK pathways (Lä uffer et al, 1999;Oh et al, 2005).…”

Secretory state regulates Zn2+ transport in gastric parietal cell of the rabbit

“…To perform these studies, the fluorescent reporter LysoSensor DND-160 was used to monitor acidity within isolated TVs. Initially, we evaluated sequestration of this reporter and its ability to monitor pH ratiometrically in isolated TVs (excitation 360 nm; emission at 460 nm and 528 nm) (3,6,19,31). In these protocols, the ratio of emission intensities (460 nm/ 528 nm) was measured in TVs (8-to 10-mg aliquots) loaded with the reporter in 96-well plates and then exposed to ICB containing the protonophores FCCP (20 M) and nigericin (7 M), adjusted to clamp pH levels over the range 3.4 -7.4.…”