Tanaka M, Kaku S, Muramatsu M, Otomo S
Department of Pharmacology, Taisho Pharmaceutical Co., Ltd., Saitama, Japan.
Eur J Pharmacol. 1993 Jul 6;238(1):93-100.
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.
我们研究了放射性标记的5,8-二甲基-4-(2-二正丙基氨基乙基)咔唑单盐酸盐([3H]FH-510)，一种高效且选择性的σ配体，与豚鼠脑膜结合的特性。[3H]FH-510与σ结合位点表现出饱和且可逆的结合。[3H]FH-510的缔合速率常数(k+1)和解离速率常数(k-1)分别为0.023 min-1·nM-1和0.081 min-1。Scatchard图分析显示解离常数(Kd)和最大结合位点数(Bmax)分别为6.0±0.63 nM和1763.3±177.4 fmol/mg蛋白质(n = 7)。通过[3H]FH-510结合取代得到的几种结构不同的σ配体的效价顺序(Ki)与通过3H-3-(3-羟基苯基)-N-(1-丙基)哌啶(3H-3-PPP)结合测定的顺序高度相关。在10(-7) M时，组胺能、多巴胺能、肾上腺素能、5-羟色胺能或胆碱能药物不影响[3H]FH-510的结合。在小脑和脑桥加延髓中观察到[3H]FH-510与脑区的结合较高。除核部分外，在微粒体部分观察到[3H]FH-510和3H-3-PPP与亚细胞部分的结合水平最高。从这些结果表明，FH-510以高亲和力选择性地结合豚鼠膜中的σ结合位点。
