Ge J, Towers P, Patel A C, Barnes N M
Department of Pharmacology, Medical School, University of Birmingham, Edgbaston, UK.
Eur J Pharmacol. 1996 Apr 4;300(1-2):113-7. doi: 10.1016/0014-2999(95)00854-3.
Autoradiographic binding studies using [125I]S(-)-zacopride (0.1 nM) identified non-5-HT3 specific binding sites (defined by 5-hydroxytryptamine (5-HT), 1.0 microM) in the rat duodenum and ileum and some other peripheral tissues (adrenal gland, liver, stomach, kidney and spleen). In the rat duodenum and ileum, saturation studies with [125I]S(-)-zacopride indicated that the specific binding was saturable and of high affinity to an apparently homogenous population of binding sites (duodenum Bmax = 1.88 fmol/mg, Kd = 0.078 nM; ileum Bmax = 1.60 fmol/mg, Kd = 0.071 nM). Competition studies with slices of either duodenum or ileum indicated that the pharmacology of the [125I]S(-)-zacopride recognition site in both tissues was comparable but differed from all 5-HT receptors and uptake sites reported to date. However, the [125I]S(-)-zacopride recognition site displayed some pharmacological and regional similarity to the 5-HT1P recognition site: The sensitivity of the [125I]S(-)-zacopride binding in the duodenum and ileum to GTP indicates that the radiolabelled recognition site may represent a functional G-protein coupled receptor.
使用[125I]S(-)-扎考必利（0.1 nM）进行的放射自显影结合研究在大鼠十二指肠、回肠以及其他一些外周组织（肾上腺、肝脏、胃、肾脏和脾脏）中鉴定出非5-羟色胺3（5-HT3）特异性结合位点（由5-羟色胺（5-HT）1.0 microM定义）。在大鼠十二指肠和回肠中，用[125I]S(-)-扎考必利进行的饱和研究表明，特异性结合是可饱和的，并且对明显同质的结合位点群体具有高亲和力（十二指肠Bmax = 1.88 fmol/mg，Kd = 0.078 nM；回肠Bmax = 1.60 fmol/mg，Kd = 0.071 nM）。对十二指肠或回肠切片进行的竞争研究表明，两种组织中[125I]S(-)-扎考必利识别位点的药理学特性具有可比性，但与迄今报道的所有5-HT受体和摄取位点不同。然而，[125I]S(-)-扎考必利识别位点与5-HT1P识别位点在药理学和区域上具有一些相似性：十二指肠和回肠中[125I]S(-)-扎考必利结合对鸟苷三磷酸（GTP）的敏感性表明，放射性标记的识别位点可能代表一种功能性G蛋白偶联受体。
