Identification and localization of extracellular Ca²⁺-sensing receptor in rat intestine

Abstract

The extracellular calcium ([Formula: see text])-sensing receptor (CaR) plays vital roles in [Formula: see text] homeostasis, but no data are available on its expression in small and large intestine. Polymerase chain reaction products amplified from reverse-transcribed duodenal RNA using CaR-specific primers showed >99% homology with the rat kidney CaR. Northern analysis with a CaR-specific cRNA probe demonstrated 4.1- and 7.5-kb transcripts in all intestinal segments. Immunohistochemistry with CaR-specific antisera showed clear basal staining of epithelial cells of small intestinal villi and crypts and modest apical staining of the former, whereas there was both basal and apical staining of colonic crypt epithelial cells. In situ hybridization and immunohistochemistry also demonstrated CaR expression in Auerbach’s myenteric plexus of small and large intestines and in the submucosa in the region of Meissner’s plexus. Our results reveal CaR expression in several cell types of small and large intestine, in which it may modulate absorptive and/or secretomotor functions.

Immunocytochemical Localization of the Extracellular Calcium-Sensing Receptor in Normal and Malignant Human Large Intestinal Mucosa

“…Apart from human colon adenocarcinoma-derived cell lines such as Caco-2 (Kállay et al 1997) or T84 and HT-29 (Gama et al 1997), the presence of the CaR has been shown in normal rat small and large intestine (Gama et al 1997;Chattopadhyay et al 1998). In this study we were able to show that human colon mucosal cells also express the CaR at the message and protein level (cf.…”

Calcium-sensing receptor abrogates secretagogue- induced increases in intestinal net fluid secretion by enhancing cyclic nucleotide destruction

“…Epithelial cells along the entire length of the intestine express the CaSR (8-10); however, the functions of this receptor in the gastrointestinal tract are only beginning to be understood (11). The CaSR has been identified on both the luminal and basolateral sides of human (10,12) and rat colonocytes (8,10), and receptors on both sides of this polarized epithelium can be activated by extracellular calcium and other polycations like spermine (9,10). CaSR activation of G q in colonocytes (10), as well as other cell types (2), results in a rise in intracellular Ca 2ϩ via activation of phospholipase C (PLC), formation of IP 3 , and subsequent Ca 2ϩ release from IP 3 -sensitive cytosolic stores (10).…”

Effect of dietary components on renal inorganic phosphate (Pi) excretion induced by a Pi-depleted diet

“…The CaR, a G protein-coupled receptor, is best known and understood for its control of PTH synthesis and secretion in response to changes in Ca, Mg, Sr, and La (17,18). CaRs are distributed along most of the gastrointestinal tract, from the stomach to the large intestine (23,28). The physiologic role of CaRs is the maintenance of constant blood Ca 2 + levels (1.1-1.3 mM) through continuous adjustments of PTH release from the parathyroid chief cells, which are highly sensitive to the slightest changes in extracellular Ca ion concentrations (17,18).…”