Interaction of somatostatin with isolated cytosol from rabbit renal papilla

Abstract Specific binding sites for somatostatin have been characterized in cytosolic fraction of rabbit renal papilla. The interaction of 125 I-Tyr 11 -somatostatin with cytosolic fraction was rapid, reversible, specific, saturable and dependent on temperature. At 25°C the binding data were compatible with the existence of two classes of binding sites: a high-affinity class with a K d =57.7 nM and a low-affinity class with a K d =217.4 nM . Somatostatin binding sites exhibited a high degree of specificity since neuropeptides such as Leu-enkephalin, neurotensin, substance P, vasopressin and vasoactive intestinal peptide behaved as ligands with null or very low affinity.