苯并恶嗪衍生物Y-25130对离体青蛙感觉神经元中5-HT3受体介导电流的阻断作用

Blockade of 5-HT3 receptor-mediated currents in dissociated frog sensory neurones by benzoxazine derivative, Y-25130.

作者信息

Yakushiji T, Akaike N

机构信息

Research Laboratories, Yoshitomi Pharmaceutical Industries Ltd., Japan.

出版信息

Br J Pharmacol. 1992 Nov;107(3):853-7. doi: 10.1111/j.1476-5381.1992.tb14536.x.

DOI:10.1111/j.1476-5381.1992.tb14536.x

PMID:1472977

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1907744/

Abstract

The effect of Y-25130, ((+-)-N-(1-azabicyclo[2.2.2]oct-3-yl)-6-chloro-4-methyl-3-oxo-3,4-dih ydr o- 2H-1,4-benzoxazine-8-carboxamide hydrochloride), a high affinity 5-hydroxytryptamine3 (5-HT3) receptor ligand, was examined on the 5-HT-induced response in dissociated frog dorsal root ganglion (DRG) neurones by use of the extremely rapid concentration-jump ('concentration-clamp') and the conventional whole-cell patch-clamp techniques. 2. 5-HT induced a rapid transient inward current associated with an increase in membrane conductance at a holding potential of -70 mV. The current amplitude increased sigmoidally as 5-HT concentration increased. The half-maximum value (Ka) and the Hill coefficient estimated from the concentration-response curve were 1.7 x 10(-5) M and 1.7, respectively. 3. The current-voltage (I-V) relationship of 5-HT-induced current (I5-HT) showed inward rectification at potentials more positive than -40 mV. The reversal potential (E5-HT) was -11 mV. The E5-HT value was unaffected by total replacement of intracellular K+ by Cs+, indicating that the 5-HT-gated channels might be large cation channels. 4. Both the activation and inactivation phases of I5-HT were single exponentials. The time constants of activation and inactivation (tau a and tau i) decreased with increasing 5-HT concentration. 5. The 5-HT response was mimicked by a selective 5-HT3 receptor agonist, 2-methyl-5-HT, but the maximum response induced was approximately 25% that of 5-HT. The 5-HT response was reversibly antagonized by the 5-HT3 receptor antagonists, ICS 205-930, metoclopramide and Y-25130, but not by a 5-HTIA receptor antagonist, spiperone, and a 5-HT2 receptor antagonist, ketanserin. The half-inhibition concentrations (IC50) were 4.9 x 10-10 M for Y-25130, 4.8 x 10-10 M for ICS 205-930 and 8.6 x 10-9 M for metoclopramide.6. Y-25130 (5 x 10-10 M) caused a rightward shift of the concentration-response curve for 5-HT while decreasing the maximum response.7. The results suggest that Y-25130 is a potent antagonist of the 5-HT3 receptor-channel complex.

摘要

研究了高亲和力5-羟色胺3（5-HT3）受体配体Y-25130（（±）-N-（1-氮杂双环[2.2.2]辛-3-基）-6-氯-4-甲基-3-氧代-3,4-二氢-2H-1,4-苯并恶嗪-8-甲酰胺盐酸盐）对离体青蛙背根神经节（DRG）神经元中5-HT诱导反应的影响，采用了极快速的浓度阶跃（“浓度钳”）和传统的全细胞膜片钳技术。2. 在-70 mV的钳制电位下，5-HT诱导出一种快速的瞬时内向电流，伴有膜电导增加。电流幅度随5-HT浓度增加呈S形增加。从浓度-反应曲线估计的半数最大值（Ka）和希尔系数分别为1.7×10⁻⁵ M和1.7。3. 5-HT诱导电流（I5-HT）的电流-电压（I-V）关系在电位高于-40 mV时显示内向整流。反转电位（E5-HT）为-11 mV。用Cs⁺完全替代细胞内K⁺时，E5-HT值不受影响，表明5-HT门控通道可能是大阳离子通道。4. I5-HT的激活和失活阶段均为单指数形式。激活和失活的时间常数（τa和τi）随5-HT浓度增加而减小。5. 5-HT反应可被选择性5-HT3受体激动剂2-甲基-5-HT模拟，但诱导的最大反应约为5-HT的25%。5-HT反应可被5-HT3受体拮抗剂ICS 205-930、甲氧氯普胺和Y-25130可逆性拮抗，但不受5-HT1A受体拮抗剂螺哌隆和5-HT2受体拮抗剂酮色林的影响。Y-25130的半数抑制浓度（IC50）为4.9×10⁻¹⁰ M，ICS 205-930为4.8×10⁻¹⁰ M，甲氧氯普胺为8.6×10⁻⁹ M。6. Y-25130（5×10⁻¹⁰ M）使5-HT的浓度-反应曲线向右移动，同时降低最大反应。7. 结果表明Y-25130是5-HT3受体-通道复合物的强效拮抗剂。