Pharmacological analysis of CCK2 receptor ligands using COS-7 and SK-N-MC cells, expressing the human CCK2 receptor

• A series of CCK2 receptor ligands were analysed with respect to their interaction with binding sites in the membranes of COS-7 cells and SK-N-MC cells transiently expressing the human CCK2 receptor (short isoform). The ligands were YF476, YM022, AG041R, L-740,093, JB93182, PD134308, and PD136450. Their binding was analysed by radioligand competition using [H-3]L-365,260 as the labelled ligand. Saturation binding analysis indicated that [H-3]L-365,260 interacted with a single class of binding sites. In competition binding experiments using COS-7-cell membranes, all seven ligands were incubated together with 2 nM [H-3]L-365,260. The data for four of the compounds fitted a one-site model (pK(i) values: YM022: 9.2 +/- 0.02, YF476: 9.6 +/- 0.04; L-740,093: 9.2 +/- 0.01, and AG041R: 8.3 +/- 0.06), while the data for the three others fitted a two-site model (pK(i) values: JB93182: 8.8 +/- 0.04 and 6.0 +/- 0.15; PD 134308: 9.0 +/- 0.04 and 6.1 +/- 0.15; and PD 136450: 9.0 +/- 0.02 and 5.4 +/- 0.41). SK-N-MC cell membranes and 2 nM [H-3]L-365,260 were incubated together with YM022, YF476, JB93182, and PD134308. The data for YM022 and YF476 fitted a one-site model (pKi values: YM022: 9.3 +/- 0.06, YF476: 9.4 +/- 0.02), while the data for JB93182 and PD134308 fitted a two-site model (pK(i) values: JB93182: 8.7 +/- 0.06 and 6.2 +/- 0.06; PD134308: 9.1 +/- 0.06 and 7.0 +/- 0.17). Competition binding experiments in the presence of the GTP-analogue guanylylimidodiphosphate, using either of the two cell types, produced similar binding data for PD 134308 and JB93182 as in the absence of GTP-analogue. The human receptor seems to exist in a low and/or high affinity state. The shift from low to high affinity does not seem to reflect the degree of G protein coupling.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Cell- och molekylärbiologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Cell and Molecular Biology (hsv//eng)

Nyckelord

CCK-B/gastrin receptor

CCK2 receptor

CCK2 receptor ligand

CCK-B/gastrin receptor ligand

human

MEDICINE

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