Expression of an extracellular calcium-sensing receptor in rat stomach.
OBJECTIVE
Circulating levels of Ca2+ can influence secretory functions and myoelectrical properties of the stomach. A Ca2+-sensing receptor (CaR) has recently been identified in tissues that regulate systemic Ca2+ homeostasis. The aim of this study was to evaluate expression of CaR in the stomach of the rat.


METHODS
In forestomach and glandular stomach, reverse-transcription polymerase chain reaction was used to amplify a 380-base pair product, which is 99% homologous with transcripts obtained in parathyroid and kidney.


RESULTS
Northern analysis of gastric mucosal polyA+ RNA revealed 7. 5- and 4.1-kilobase transcripts, similar to those obtained in rat parathyroid and kidney. Immunohistochemistry revealed CaR expression in regions of the submucosal plexus and myenteric neurons. In sections of intact tissue, preparations of primary culture surface cells and surgically dissected gastric glands, staining was observed consistently in epithelial cells of the gastric glands and in gastric surface cells. In parietal cells in isolated gastric glands, intracellular levels of Ca2+ responded to conditions that are known to activate CaR.


CONCLUSIONS
These are the first reported observations that CaR is expressed in different epithelial cells of mammalian gastric mucosa and its enteric nerve regions. The effects of extracellular Ca2+ on gastric function may be attributable to activation of CaR.
Cheng
I
I
Department of Surgery, Brigham and Women's Hospital, and West Roxbury Veterans Administration Medical Center, Harvard Medical School, Boston, Massachusetts, USA.
Qureshi
I
I
Chattopadhyay
N
N
Qureshi
A
A
Butters
R R
RR
Hall
A E
AE
Cima
R R
RR
Rogers
K V
KV
Hebert
S C
SC
Geibel
J P
JP
Brown
E M
EM
Soybel
D I
DI
D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D018076:DNA, Complementary / Q000235:genetics; D005110:Extracellular Space / Q000378:metabolism*; D005753:Gastric Mucosa / Q000166:cytology / Q000378:metabolism*; D007150:Immunohistochemistry; D008969:Molecular Sequence Data; D009130:Muscle, Smooth / Q000166:cytology / Q000378:metabolism; D010295:Parietal Cells, Gastric / Q000378:metabolism; D012313:RNA / Q000096:biosynthesis / Q000302:isolation & purification; D051381:Rats; D017207:Rats, Sprague-Dawley; D044169:Receptors, Calcium-Sensing; D011956:Receptors, Cell Surface / Q000096:biosynthesis* / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013270:Stomach / Q000166:cytology; D014158:Transcription, Genetic
D018076:DNA, Complementary; D044169:Receptors, Calcium-Sensing; D011956:Receptors, Cell Surface; C473605:extracellular calcium cation-sensing receptor, rat; D012313:RNA; D002118:Calcium