title: Ca2+-sensing receptors in intestinal epithelium.
abstract: Expression of Ca2+-sensing receptors (CaR) was demonstrated in several human intestinal epithelial cell lines (T84, HT-29, and Caco-2) and in rat intestinal epithelium by both reverse transcriptase-polymerase chain reaction (PCR) and Northern blotting of RNA. Restriction patterns of the PCR products were of the sizes predicted by the human and rat sequences. CaR agonists (Ca2+, poly-L-arginine, protamine) mediated an increase in intracellular Ca2+ in HT-29-18-C1 cells (monitored by changes in fura 2 fluorescence), which was dependent on release from thapsigargin-sensitive stores. U-73122, an inhibitor of phosphatidylinositol-phospholipase C, eliminated the CaR agonist-mediated rise in intracellular Ca2+, whereas its inactive analog, U-73343, had no effect. Pertussis toxin pretreatment had no effect on CaR agonist-mediated modulation of intracellular Ca2+. Taken together, these studies demonstrate that CaR are expressed in intestinal epithelial cells and couple to mobilization of intracellular Ca2+. The presence of CaR in intestinal epithelial cells presents a new locus for investigations into the role(s) of extracellular Ca2+ in modulating intestinal epithelial cell differentiation and transepithelial Ca2+ transport.
authors.affiliation: Department of Physiology, School of Medicine, Johns Hopkins University, Baltimore, Maryland 21205, USA.
authors.forename: L
authors.initials: L
authors.lastname: Gama
authors.forename: L M
authors.initials: LM
authors.lastname: Baxendale-Cox
authors.forename: G E
authors.initials: GE
authors.lastname: Breitwieser
mesh_terms: D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002432:Cecum; D002460:Cell Line; D003106:Colon; D017931:DNA Primers; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004963:Estrenes / Q000494:pharmacology; D005091:Exons; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D007421:Intestine, Small; D007438:Introns; D007700:Kinetics; D009496:Neurotensin / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D016133:Polymerase Chain Reaction; D011760:Pyrrolidinones / Q000494:pharmacology; D051381:Rats; D044169:Receptors, Calcium-Sensing; D011956:Receptors, Cell Surface / Q000096:biosynthesis* / Q000235:genetics; D019284:Thapsigargin / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects; D014407:Tumor Cells, Cultured; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors
chemical_list: D017931:DNA Primers; D004791:Enzyme Inhibitors; D004963:Estrenes; D010455:Peptides; D011760:Pyrrolidinones; D044169:Receptors, Calcium-Sensing; D011956:Receptors, Cell Surface; C473605:extracellular calcium cation-sensing receptor, rat; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C015462:polyarginine; D009496:Neurotensin; D019284:Thapsigargin; D010738:Type C Phospholipases; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D002118:Calcium