Characterisation of 5-HT3 recognition sites in membranes of NG 108-15 neuroblastoma-glioma cells with [3H]ICS 205-930.
1. The binding characteristics of [3H]ICS 205-930, a potent and selective 5-hydroxytryptamine 5-HT3 receptor antagonist, were investigated in membranes prepared from murine neuroblastoma-glioma NG 108-15 cells. 2. [3H]ICS 205-930 bound rapidly, reversibly and stereoselectively to a homogeneous population of high affinity recognition sites: Bmax = 58 +/- 3 fmol/mg protein, pKD = 9.01 +/- 0.08 (n = 11). Non linear regression and Scatchard analysis of saturation data suggested the existence of a single class of [3H]ICS 205-930 recognition sites on NG 108-15 cells. The binding was rapid, stable and reversible. The affinity of [3H]ICS 205-930 determined in kinetic studies was in agreement with that obtained under equilibrium conditions. 3. Competition studies performed with a variety of agonists and antagonists also suggested the presence of a homogeneous population of [3H]ICS 205-930 recognition sites. All competition curves were steep and monophasic and were best fit by a 1 receptor site model. [3H]ICS 205-930 binding sites displayed the pharmacological profile of a 5-HT3 receptor. Potent 5-HT3 receptor antagonists showed nanomolar affinities for [3H]ICS 205-930 binding sites with the following rank order of potency: SDZ 206-830 greater than ICS 205-930 greater than SDZ 206-792 greater than BRL 43694 greater than quipazine greater than BRL 24924 greater than SDZ 210-204 greater than MDL 72222 greater than SDZ 210-205. Metoclopramide, mCP and mianserin showed submicromolar affinity.(ABSTRACT TRUNCATED AT 250 WORDS)
Neijt
H C
HC
Department of Veterinary Pharmacology, Pharmacy and Toxicology, University of Utrecht, The Netherlands.
Karpf
A
A
Schoeffter
P
P
Engel
G
G
Hoyer
D
D
D000818:Animals; D001667:Binding, Competitive / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects; D005910:Glioma / Q000378:metabolism; D007211:Indoles; D007700:Kinetics; D051379:Mice; D009447:Neuroblastoma / Q000378:metabolism; D009711:Nucleotides / Q000494:pharmacology; D011869:Radioligand Assay; D011985:Receptors, Serotonin / Q000032:analysis*; D012702:Serotonin Antagonists; D013237:Stereoisomerism; D013696:Temperature; D000077526:Tropisetron; D014407:Tumor Cells, Cultured / Q000378:metabolism*
D007211:Indoles; D009711:Nucleotides; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D000077526:Tropisetron