Agonist activity at human somatostatin 4 receptor expressed in H4 cells assessed as inhibition of forskolin-induced intracellular cAMP accumulation incubated for 60 mins by time-resolved fluorescence assay
Displacement of [3-125l-Tyr]-somatostatin-(1 -14) from human recombinant somatostatin 4 receptor expressed in CHO cell membranes incubated for 180 mins
Agonist activity at recombinant human sst4 receptor expressed in CHOK1 cells co-expressing Galpha16 assessed as induction of cytoplasmic calcium mobilization at 250 uM measured for 40 secs by fluorometric analysis relative to L-803087
Radioligand Binding Assay: Membranes for in vitro receptor binding assays were obtained by the following procedures. CHO-K1 cells expressing one of the somatostatin receptors were homogenized in ice-cold buffer with 10 mM Tris-HCl, 5 mM EDTA, 3 mM EGTA, 1 mM phenylmethylsuphonyl fluoride, pH 7.6, using Polytron PT10-35GT (Kinematica) at 18,000 rpm for 30 seconds and centrifuged at 500xg for 10 minutes. The supernatant containing the plasma membranes was centrifuged at 100,000xg for 30 minutes and the pellet was resuspended in buffer containing 20 mM glycine-glycine, 1 mM MgCl2, 250 mM sucrose, pH 7.2, for storage at -80 C.For the SSTR1, 2 and 5 assays, membranes and various concentrations of test compounds were incubated in 96-well plates for 60 minutes at 25 C. with 0.05 nM [125I-Tyr11]-SRIF-14 (for hSSTR1; PerkinElmer Life Science), 0.05 nM [125I-Tyr]-seglitide (for hSSTR2; PerkinElmer Life Science) or 0.05 nM [125I-Tyr]-[DPhe-cyclo(Cys-Tyr-DTrp-Lys-Val-Cys)-Thr-NH2] (for hSSTR5.
Displacement of [125I]Tyr11-somatostatin-14 from human recombinant SST4 receptor expressed in CHO cells assessed as remaining radioligand binding at 10 uM after 120 mins by scintillation counting method relative to control