Somatostatin binding sites in cytosolic fractions of parietal and non-parietal cells from rabbit fundic mucosa.

Specific binding sites for somatostatin have been found in the cytosolic fractions of both parietal and non-parietal cells from rabbit gastric fundic mucosa. The stoichiometric data suggested the presence of two classes of binding sites in both types of cells. The number of low-affinity binding sites was significantly higher in parietal cells than in non-parietal cells. The reverse was true for the high-affinity binding sites. However, the affinity of each class of binding sites was similar in the cytosolic fractions of both parietal and non-parietal cells. It thus appears that low-affinity somatostatin binding sites are mainly located in the parietal cells whereas the high-affinity sites occur principally in the non-parietal cells.