Characterisation of human recombinant somatostatin receptors. 2. Modulation of GTPγS binding

Abstract

G protein activation by somatostatin (somatotropin release inhibiting factor, SRIF), cortistatin (CST) and analogues of these neuropeptides was investigated at human somatostatin receptor subtypes 1-5 (sst1-5) stably expressed in CCL39 Chinese hamster lung fibroblast cells by measuring agonist-stimulated [35S]guanosine 5'-O-(3-thiotriphosphate) ([35S]GTPγS) binding. [35S]GTPγS binding was assessed in the presence of 100 mM NaCl and 1 μM GDP, although higher E(max) and/or pEC50 values may have been obtained under other conditions, but at the expense of lower absolute stimulation or signal/noise ratio. SRIF14 stimulated [35S]GTPγS binding to 162, 220, 148 and 266% of control levels via sst2, s..