Kaumann A J, Lynham J A, Brown A M
Human Pharmacology Laboratory, Babraham Institute, Cambridge, UK.
Naunyn Schmiedebergs Arch Pharmacol. 1996 Apr;353(5):592-5. doi: 10.1007/BF00169181.
We measured in human atrium the density of 5-HT4 receptors, labelled with [125I]-SB 207710 (1-butyl-4-piperidinyl) methyl 8-amino-7-iodo-1, 4-benzodioxan-5-carboxylate), and compared it with the density of beta1- and beta2-adrenoceptors, labelled with (-)-[125I]-cyanopindolol. [125I]-SB 207710 (5-1200 pmol/l) labelled a small population of saturable binding sites (Bmax approximately 4 fmol/mg protein) with a pK(D) of 9.7 and with 5-HT4 receptor characteristics, as assessed with competing ligands. The density of atrial binding sites with 5-HT4 receptor characteristics was 10 and 5 times lower, respectively, than the density of beta 1- and beta 2-adrenoceptors. We suggest that the small 5-HT4 receptor population may in part explain why the positive inotropic effects of 5-HT are smaller than those of catecholamines mediated through beta 1- and beta 2-adrenoceptors.
我们测定了人心房中用[125I]-SB 207710（1-丁基-4-哌啶基）甲基8-氨基-7-碘-1,4-苯并二恶烷-5-羧酸盐标记的5-HT4受体的密度，并将其与用（-）-[125I]-氰基吲哚洛尔标记的β1和β2肾上腺素能受体的密度进行比较。[125I]-SB 207710（5-1200 pmol/l）标记了一小部分可饱和结合位点（Bmax约为4 fmol/mg蛋白质），其pK（D）为9.7，具有5-HT4受体特征，这是通过竞争性配体评估得出的。具有5-HT4受体特征的心房结合位点的密度分别比β1和β2肾上腺素能受体的密度低10倍和5倍。我们认为，少量的5-HT4受体群体可能部分解释了为什么5-HT的正性肌力作用小于通过β1和β2肾上腺素能受体介导的儿茶酚胺的正性肌力作用。
