The ligands interacting with enterochromaffin-like (ECL) and parietal cells
and the signaling interactions between these cells were investigated in ra
bbit gastric glands using confocal microscopy. Intracellular calcium concen
tration ([Ca2+](i)) changes were used to monitor cellular responses. Histam
ine and carbachol increased [Ca2+](i) in parietal cells. Gastrin (1 nM) inc
reased [Ca2+](i) in ECL cells and adjacent parietal cells. Only the increas
e of [Ca2+](i) in parietal cells was inhibited by H-2 receptor antagonists
(H(2)RA). Gastrin (10 nM) evoked an H(2)RA-insensitive [Ca2+](i) increase i
n parietal cells. Carbachol produced large H(2)RA- and somatostatin-insensi
tive signals in parietal cells. Pituitary adenylate cyclase-activating pept
ide (PACAP, 100 nM) elevated [Ca2+](i) in ECL cells and adjacent parietal c
ells. H2RAs abolished the PACAP-stimulated [Ca2+](i) increase in adjacent p
arietal cells. Somatostatin did not inhibit the increase of [Ca2+](i) in pa
rietal cells stimulated with histamine, high gastrin concentrations, or car
bachol but abolished ECL cell calcium responses to gastrin or PACAP. Hence,
rabbit parietal cells express histaminergic, muscarinic, and CCK-B recepto
rs coupled to calcium signaling but insensitive to somatostatin, whereas ra
bbit and rat ECL cells express PACAP and CCK-B calcium coupled receptors se
nsitive to somatostatin.