Localization of the histamine H2 receptor and gene transcripts in rat stomach: back to parietal cells.
ABSTRACT In contrast with many physiological studies suggesting that histamine H2 receptors are present on acid-secreting parietal cells of the gastric epithelium, it was recently shown that immune cells in the lamina propria are the only cells expressing H2-receptor mRNAs (Mezey and Palkovits, Science, 1992, 258, 1662-1665). We have reinvestigated the cellular localization of H2 receptors in the rat stomach by visualizing both the H2 receptor mRNA and the H2-receptor protein itself. In situ hybridization histochemistry performed with an antisense riboprobe for the rat H2 receptor, and autoradiographic distribution of 125I-aminopotentidine binding sites, a highly selective H2-receptor ligand, did not show any labeling of the lamina propria. Signals were clearly and solely detected in the gastric epithelium, the strongest being observed in the upper part of the glands where the H2 receptor gene transcripts were only detected within parietal cells. In situ hybridization performed with an antisense riboprobe for L-histidine decarboxylase mRNA confirmed the basal localization of the histamine-synthetizing cells in the rat gastric gland, at some distance from parietal histamine-sensitive cells.
SourceAvailable from: Wen-Xie Xu[Show abstract] [Hide abstract]
ABSTRACT: This study was designed to examine the effects of histamine on gastric motility and its specific receptor in the circular smooth muscle of the human gastric corpus. Histamine mainly produced tonic relaxation in a concentration-dependent and reversible manner, although histamine enhanced contractility in a minor portion of tissues tested. Histamine-induced tonic relaxation was nerve-insensitive because pretreatment with nerve blockers cocktail (NBC) did not inhibit relaxation. Additionally, K(+) channel blockers, such as tetraethylammonium (TEA), apamin (APA), and glibenclamide (Glib), had no effect. However, N(G)-nitro-L-arginine methyl ester (L-NAME) and 1H-(1,2,4)oxadiazolo (4,3-A) quinoxalin-1-one (ODQ), an inhibitor of soluble guanylate cyclase (sGC), did inhibit histamine-induced tonic relaxation. In particular, histamine-induced tonic relaxation was converted to tonic contraction by pretreatment with L-NAME. Ranitidine, the H2 receptor blocker, inhibited histamine-induced tonic relaxation. These findings suggest that histamine produced relaxation in circular smooth muscle of human gastric smooth muscle through H2 receptor and NO/sGC pathways.Korean Journal of Physiology and Pharmacology 10/2014; 18(5):425-30. DOI:10.4196/kjpp.2014.18.5.425 · 1.26 Impact Factor
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ABSTRACT: Conformational analysis and geometry optimization of flavanoid derivative 2-phenyl-4H-chromen-4-ones, as a histamine H 1 receptor antagonist, was performed according to the Hartree-Fock (HF) calculation method by ArgusLab 4 software . The result indicates that the best conformation of the molecule is present at minimum potential energy is found to be -68696.5088 kcal/mol. At this point molecule will be more active as histamine H 1 receptor antagonist.
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ABSTRACT: We previously found that parietal cells in guinea pigs starved for a few days contained giant mitochondria while the cells of animals starved and then injected with histamine mostly did not. To test whether mitochondria change their size and activity according to energy demands for acid secretion, we examined the dynamics of mitochondria stained by rhodamine 123 in living parietal cells in gastric glands under a confocal microscope. The glands were isolated from guinea pigs starved for 60-72 hr. Because mitochondria were closely packed in the cytoplasm, we failed to observe the morphological changes of each mitochondrion in parietal cells. However, we successfully observed that 10(-5) M histamine induced an increase in the fluorescence intensity (the concentration of rhodamine 123) in mitochondria in subpopulations of parietal cells; the fluorescence intensity increased sharply within minutes after the histamine administration in some cells, while it gradually increased from just after the administration in other cells. We also found that a subpopulation of mitochondria within a parietal cell responded to the secretagogue. The findings suggest that parietal cells exist as a heterogeneous population in gastric glands and contain heterogeneous mitochondria in terms of their mitochondrial response to histamine.Acta histochemica et cytochemica official journal of the Japan Society of Histochemistry and Cytochemistry 01/2003; 36(4):255-262. DOI:10.1267/ahc.36.255 · 1.22 Impact Factor