Competitive antagonism of the mouse 5-hydroxytryptamine₃ receptor by bisindolylmaleimide I, a "selective" protein kinase C inhibitor

作     者：Coultrap, SJ Sun, HW Tenner, TE Machu, TK 

作者机构：Texas Tech Univ Hlth Sci Ctr Dept Pharmacol Lubbock TX 79430 USA 

出 版 物：《JOURNAL OF PHARMACOLOGY AND EXPERIMENTAL THERAPEUTICS》 (药理学与实验治疗学杂志)

年 卷 期：1999年第290卷第1期

页      面：76-82页

核心收录：

学科分类：1007[医学-药学(可授医学、理学学位)] 1006[医学-中西医结合] 100706[医学-药理学] 100602[医学-中西医结合临床] 10[医学] 

主　　题：生物碱类 苯并菲啶类 结合 竞争性 细胞膜/代谢 DNA/生物合成 酶抑制剂/药理学 吲哚类/拮抗剂和抑制剂 吲哚类/药理学 马来酰亚胺类/拮抗剂和抑制剂 马来酰亚胺类/药理学 萘类/药理学 卵母细胞/代谢 膜片钳术 菲啶类/药理学 蛋白激酶C/拮抗剂和抑制剂 RNA/生物合成 受体 血清素/生物合成 受体 血清素/药物作用 受体 血清素/遗传学 受体 血清素 5-HT3 血清素拮抗药/药理学 星状孢子素/药理学 爪蟾 光滑 动物 小鼠 

摘      要：We examined the effects of several protein kinase C (PKC) inhibitors on the murine 5-hydroxytryptamine(3) (5-HT3) receptor to determine whether they acted directly on the receptor. The 5-HT-evoked currents in Xenopus laevis oocytes expressing the recombinant 5-HT3 receptor were measured with the two-electrode voltage-clamp technique. The PKC inhibitors bisindolylmaleimide I (BIM, GF109203x) and staurosporine, but not calphostin C or chelerythrine, decreased the 5-HT3 receptor-mediated currents when coapplied with 5-HT. BIM blocked 0.5 mu M 5-MT-elicited currents with an IC50 value of 7 nM, whereas in the presence of 5 mu M staurosporine, 42% inhibition of 0.5 mu M 5-HT-mediated currents was observed. Increasing concentrations of BIM resulted in a rightward shift of the 5-HT concentration-response curve, without altering efficacy. A Schild plot was generated, which had a slope of -1.01, suggesting competitive antagonism. The K-i value of BIM was determined to be 29 nM. To confirm competitive antagonism, a competitive binding assay was performed on Sf21 insect cells infected with the mouse 5-HT3 receptor cDNA in a baculovirus expression vector. BIM completely displaced binding of the selective 5-HT3 receptor antagonist [H-3]GR65630. BIM bound to the 5-HT3 receptor with a K-i value of 61 nM, which was slightly less potent than that of the selective 5-MT, receptor antagonist MDL72222 (27 nM). The PKC inhibitor BIM is a potent competitive antagonist at the 5-HT3 receptor.