IDENTIFICATION AND LOCALIZATION OF EXTRACELLULAR CA2-SENSING RECEPTORIN RAT INTESTINE()

The extracellular calcium (Ca-0(2+))-sensing receptor (CaR) plays vita l roles in Ca-0(2+) homeostasis, but no data are available on its expr ession in small and large intestine. Polymerase chain reaction product s amplified from reverse-transcribed duodenal RNA using CaR-specific p rimers showed >99% homology with the rat kidney CaR. Northern analysis with a CaR-specific cRNA probe demonstrated 4.1- and 7.5-kb transcrip ts in all intestinal segments. Immunohistochemistry with CaR-specific antisera showed clear basal staining of epithelial cells of small inte stinal villi and crypts and modest apical staining of the former, wher eas there was both basal and apical staining of colonic crypt epitheli al cells. In situ hybridization and immunohistochemistry also demonstr ated CaR expression in Auerbach's myenteric plexus of small and large intestines and in the submucosa in the region of Meissner's plexus. Ou r results reveal CaR expression in several cell types of small and lar ge intestine, in which it may modulate absorptive and/or secretomotor functions.