CANINE PARIETAL-CELL BINDING BY ANTIBODIES TO THE COMPLEMENTARY PEPTIDE OF SOMATOSTATIN

Using antibodies to a complementary peptide of somatostatin, putative somatostatin binding proteins were characterized on canine parietal ce lls. A synthetic peptide (S-C1) was derived from the complementary mRN A sequence for somatostatin-14. Antiserum containing antibodies to S-C 1 inhibited competitively I-125-Tyr11-somatostatin binding to canine o xyntic mucosal membranes. Canine parietal cell preparations were incub ated with carbachol in the presence or absence of somatostatin and ant isera to S-C1. Antibodies to S-C1 produced a decrease in carbachol-sti mulated C-14-aminopyrine uptake comparable with that produced by 10(-6 ) M somatostatin. In immunocytochemical studies by light microscopy, a ntibodies to S-C1 produced positive staining of parietal cells through out the oxyntic gland area. By electron microscopy using immunogold te chniques, binding by antibodies to somatostatin C-1 was localized ultr astructurally to basolateral and intracellular membranes and to secret ory canalicular membranes of parietal cells. These studies support the conclusion that antibodies to the somatostatin complementary peptide demonstrate properties similar to those of somatostatin in that they i nhibit carbachol-stimulated aminopyrine uptake and I-125-somatostatin binding. Furthermore, these antibodies localize to specific regions on plasma membranes of parietal cells, which may represent somatostatin binding sites.