N-methyl-D-aspartate receptor regulation of uncompetitive antagonist binding in rat brain membranes: kinetic analysis.
N-methyl-D-aspartate receptor regulation of uncompetitive antagonist binding in rat brain membranes: kinetic analysis.
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发表时间：
1988-09
影响因子：
3.6
通讯作者：
D. Bonhaus;J. McNamara
中科院分区：
文献类型：
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作者：
D. Bonhaus;J. McNamara
n -甲基- d -天冬氨酸（NMDA）受体配体调节非竞争性拮抗剂在大鼠脑膜中的结合。为了确定这种调节的机制，我们研究了放射性标记的非竞争性拮抗剂[3H]N-（1-[噻吩基]环己基）哌啶（TCP）的结合动力学。NMDA受体激动剂浓度的增加使TCP的缔合和解离速率常数呈剂量依赖性增加。NMDA受体拮抗剂氨基膦酸实际上消除了TCP的结合和解离。线性回归分析发现NMDA受体配体对表观缔合和解离速率常数的影响具有显著（p < 0.001）的相关性。对这些数据最简洁的解释是，NMDA受体配体通过控制TCP对位于受体偶联离子通道中的瞬时可达或“保护”结合位点的访问来调节TCP结合。TCP结合位点亲和性或数量的增加既不是必要的，也不足以解释NMDA激动剂产生的TCP结合增强。这一发现验证了非竞争性拮抗剂结合作为分离膜制剂中NMDA受体偶联离子通道功能激活的测量方法。
N-Methyl-D-aspartate (NMDA) receptor ligands regulate the binding of uncompetitive antagonists in membranes prepared from rat brain. To determine the mechanism of this regulation, we examined the kinetics of the binding of the radiolabeled uncompetitive antagonist [3H]N-(1-[thienyl]cyclohexyl) piperidine (TCP). Increasing concentrations of NMDA receptor agonists produced dose-dependent increases in the association and dissociation rate constants of TCP. The NMDA receptor antagonist amino phosphono valeric acid virtually abolished both the association and dissociation of TCP. Linear regression analysis detected a significant (p less than 0.001) correlation between the effect of NMDA receptor ligands on the apparent association and dissociation rate constants. The most parsimonious explanation of the data is that NMDA receptor ligands regulate TCP binding by controlling access of TCP to a transiently accessible or "guarded" binding site located in the receptor-coupled ion channel. An increase in affinity or number of TCP binding sites is neither necessary nor sufficient to explain the potentiation of TCP binding produced by NMDA agonists. This finding validates the use of uncompetitive antagonist binding as a measure of the functional activation of the NMDA receptor-coupled ion channel in isolated membrane preparations.