HOW QUICKLY CAN GABA(A) RECEPTORS OPEN
HOW QUICKLY CAN GABA(A) RECEPTORS OPEN
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DOI：
10.1016/0896-6273(94)90152-x
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发表时间：
1994-01-01
期刊：
影响因子：
16.2
通讯作者：
STEINBACH, JH
中科院分区：
文献类型：
--
作者：
MACONOCHIE, DJ;ZEMPEL, JM;STEINBACH, JH
我们研究了GABA（A）受体的激活，使快速应用GABA的外向补丁从培养的出生后大鼠小脑神经元。电流的发展速度随着GABA浓度的增加而增加，从低浓度到高浓度渐近线。低浓度渐近线约为10 s-1的颗粒细胞和4 s-1的浦肯野细胞的补丁。无论是颗粒细胞还是浦肯野细胞，高浓度渐近线约为6000 s ~（-1）。高浓度渐近线给出了这些通道可以打开的最快速率的估计值，并表明激动剂结合步骤不限制速率。电流发展的浓度依赖性表明多于一个GABA分子与具有开放通道的大多数受体结合，并且最终结合步骤具有低亲和力（约500 μ M）。与GABA介导的突触后电流的比较表明，GABA（A）受体的性质在决定抑制性突触反应的形状中起主要作用，并且GABA的间隙浓度至少达到500 μ M。
We have examined GABA(A) receptor activation by making rapid applications of GABA to outside-out patches excised from cultured postnatal rat cerebellar neurons. The rate of development of current increases with increasing GABA concentration from a low to a high concentration asymptote. The low concentration asymptote is about 10 s-1 for patches taken from granule cells and 4 s-1 for patches from Purkinje cells. The high concentration asymptote is about 6000 s-1 for patches taken from either granule cells or Purkinje cells. The high concentration asymptote gives an estimate of the fastest rate at which these channels can open and indicates that agonist binding steps are not rate limiting. The concentration dependence of the development of current indicates that more than one GABA molecule is bound to most receptors with open channels and that the final binding step is of low affinity (about 500 muM). A comparison with GABA-mediated postsynaptic currents suggests that the properties of the GABA(A) receptor play a major role in determining the shape of inhibitory synaptic responses and that the cleft concentration of GABA reaches at least 500 muM.