The somatostatin receptor subtype on rat enterochromaffinlike cells.
OBJECTIVE
Gastric enterochromaffinlike (ECL) cells play an important role in peripheral regulation of acid secretion. This study investigated the somatostatin receptor subtype on ECL cells.


METHODS
ECL cells were isolated from rat fundic mucosa to a purity of 90%-95% by combining enzymatic digestion, elutriation, density gradient centrifugation, and culture.


RESULTS
Polymerase chain reaction performed with templates from an ECL cell complementary DNA library and primers specific to each of the five known somatostatin receptor subtypes showed that the somatostatin receptor type 2 was significantly enriched in ECL complementary DNA. Single cell videoimaging of highly purified ECL cells in culture showed that only the somatostatin receptor type 2 selective agonist, DC 32-87, inhibited the gastrin-induced calcium signal at 10(-11) mol/L. The type 3 and type 4 selective agonists, DC 25-12 and DC 32-92, and also somatostatin 14 required 100-1000 times higher concentrations (10(-8) mol/L). The somatostatin receptor type 2 analogue also inhibited gastrin-stimulated histamine release with a 50% inhibitory concentration (IC50) value of 2 x 10(-12) mol/L, whereas somatostatin 14 and the type 3 and 4 analogues showed IC50 values of 1 to 5 x 10(-9) mol/L.


CONCLUSIONS
The predominant somatostatin receptors on rat gastric ECL cells are of the somatostatin receptor 2 subtype; they inhibit histamine secretion by interfering with the gastrin-induced calcium signal.
Prinz
C
C
Department of Medicine, UCLA.
Sachs
G
G
Walsh
J H
JH
Coy
D H
DH
Wu
S V
SV
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002118:Calcium / Q000378:metabolism; D018076:DNA, Complementary; D004759:Enterochromaffin Cells / Q000378:metabolism* / Q000502:physiology; D015723:Gene Library; D006636:Histamine Release / Q000187:drug effects; D015335:Molecular Probes / Q000235:genetics; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D051381:Rats; D017481:Receptors, Somatostatin / Q000145:classification / Q000378:metabolism*; D013004:Somatostatin / Q000819:agonists / Q000031:analogs & derivatives / Q000235:genetics
D018076:DNA, Complementary; D015335:Molecular Probes; D017481:Receptors, Somatostatin; D013004:Somatostatin; D002118:Calcium