Binding of [3H]FH-510 to sigma ligand recognition sites in guinea-pig brain membranes.
We examined the characteristics of the binding of radiolabeled 5,8-dimethyl-4-(2-di-n-propylaminoethyl)carbazol monohydrochloride ([3H]FH-510), a highly potent and selective sigma ligand, to guinea-pig brain membranes. [3H]FH-510 showed saturable and reversible binding to sigma binding sites. The association rate constant (k+1) and dissociation rate constant (k-1) of [3H]FH-510 were 0.023 min-1.nM-1 and 0.081 min-1, respectively. Scatchard plot analysis showed a dissociation constant (Kd) and maximal number of binding sites (Bmax) of 6.0 +/- 0.63 nM and 1763.3 +/- 177.4 fmol/mg protein (n = 7), respectively. The rank order of potency (Ki) of several structurally dissimilar sigma ligands obtained for the displacement of [3H]FH-510 binding was highly correlated with that determined for [3H](+)-3-(3-hydroxyphenyl)-N-(1-propyl)piperidine ([3H](+)-3-PPP) binding. The binding of [3H]FH-510 was not influenced by histaminergic, dopaminergic, adrenergic, serotonergic or cholinergic agents at 10(-7) M. Higher [3H]FH-510 binding to brain regions was observed in the cerebellum and pons-plus-medulla. Except for the nuclear fraction, the highest level of [3H]FH-510 and [3H](+)-3-PPP binding to subcellular fractions was observed in the microsomal fraction. From these results, it is suggested that FH-510 selectively binds with high affinity to sigma binding sites in guinea-pig membranes.
Tanaka
M
M
Department of Pharmacology, Taisho Pharmaceutical Co., Ltd., Saitama, Japan.
Kaku
S
S
Muramatsu
M
M
Otomo
S
S
D000818:Animals; D014151:Anti-Anxiety Agents / Q000378:metabolism; D001665:Binding Sites; D001667:Binding, Competitive / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002227:Carbazoles / Q000378:metabolism* / Q000494:pharmacology; D015259:Dopamine Agents / Q000378:metabolism; D006168:Guinea Pigs; D006632:Histamine / Q000031:analogs & derivatives / Q000378:metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D008861:Microsomes / Q000378:metabolism; D010620:Phenazocine / Q000031:analogs & derivatives / Q000378:metabolism; D010880:Piperidines / Q000378:metabolism; D011437:Propylamines / Q000378:metabolism* / Q000494:pharmacology; D011743:Pyrimidines / Q000378:metabolism; D011869:Radioligand Assay; D017480:Receptors, sigma / Q000378:metabolism*; D012701:Serotonin / Q000031:analogs & derivatives / Q000378:metabolism
D014151:Anti-Anxiety Agents; D002227:Carbazoles; D015259:Dopamine Agents; D010880:Piperidines; D011437:Propylamines; D011743:Pyrimidines; D017480:Receptors, sigma; C050408:alpha-(4-fluorophenyl)-4-(5-fluoro-2-pyrimidinyl)-1-piperazine butanol; C083362:FH 510; D012701:Serotonin; C012134:SK&F 10047; D006632:Histamine; C026539:preclamol; D010620:Phenazocine