Characterisation of human recombinant somatostatin receptors. 4. Modulation of phospholipase C activity

Abstract

Total [3H]phosphoinositide (IP(x)) accumulation, a measure of phospholipase C (PLC) activity, induced by somatostatin (somatotropin release-inhibiting factor, SRIF) and cortistatin (CST) analogues was studied at human somatostatin receptor subtypes 1-5 (hsst1-5) recombinantly expressed in CCL39 (Chinese hamster lung fibroblast) cells. SRIF14 (10 μM) stimulated total [3H]-IP(x) production 200% and 1070% over basal levels, and increased intracellular Ca2+ ([Ca2+](i)) 1600% and 2790%, in cells expressing hsst3 and hsst5 receptors, respectively. The SRIF14-stimulated IP(x) production was partly blocked by 100 ng/ml pertussis toxin (PTX) (30% and 15% inhibition, respectively). At hsst1, hsst2, an..