Kinetic properties of the GABAA receptor main conductance state of mouse spinal cord neurones in culture.
Kinetic properties of the GABAA receptor main conductance state of mouse spinal cord neurones in culture.
复制标题
培养物中小鼠脊髓神经元 GABAA 受体主要电导状态的动力学特性。
DOI：
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
R. Twyman
中科院分区：
文献类型：
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作者：
R. L. MacDonald;C. J. Rogers;R. Twyman
1.用膜片钳技术研究了细胞培养条件下小鼠脊髓神经元胞体GABA受体通道主要电导态的动力学特性。2.全细胞GABA受体电流在0.5~5微米范围内呈浓度依赖性增加。3.记录到单通道电流，主电导状态为27.2ps，次要电导状态为15.9ps。主导电态单独开启，并以多个开口的形式出现。4.随着GABA浓度从0.5微米增加到5微米，GABA受体主导电流的平均开放时间增加，开放时间频率直方图向更长时间移动。在所有GABA浓度下，需要三个指数函数来拟合直方图，这表明该通道至少开放为三种开放状态(O1、O2和O3)。三个函数具有相同的时间常数(1.0+/-0.2、3.7+/-0.4和11.3+/-0.5ms；平均值+/-S.D.)在每个浓度下。随着浓度的增加，长开放时间的增加是由于开放的相对频率从最短的(O1)状态转移到两个最长的开放状态(O2和O_3)。5.用多指数函数拟合主电导态开口处的闭合时间分布，表明该通道具有多个闭合状态。最短的两个时间常数(0.24+/-0.03和2.0+/-0.3ms)与浓度无关(0.5-5微米)。三个较长的时间常数随着浓度的增加而减小。6.爆裂的定义是被大于临界关闭时间(TC=5ms)的闭合所包围的一组开口。当GABA浓度从0.5微米增加到5微米时，平均爆发持续时间增加，爆发持续时间频率直方图向更长时间移动。猝发持续时间频率直方图最好用三个指数函数来拟合。时间常数与浓度无关，分别为1.0+/-0.2、5.5+/-0.2和29.8+/-1.6ms。爆发持续时间随着浓度的增加而增加是由于短持续时间的爆发相对转变为较长持续时间的爆发。7.最短爆发时间常数与最短开放时间常数相似，表明存在一个持续时间较短的单一开口群体。两个最长的突发时间常数大于两个最长的开放时间常数，这表明来自两个最长突发成分的突发由两个或两个以上的开口组成。
1. The kinetic properties of the main conductance state of gamma‐aminobutyric acidA (GABA) receptor channels from somata of mouse spinal cord neurones in cell culture were investigated using patch clamp techniques. 2. Whole‐cell GABA receptor currents increased in a concentration‐dependent manner from 0.5 to 5 microM. 3. Single‐channel currents were recorded with a main conductance state of 27.2 pS and a less frequent conductance state of 15.9 pS. The main conductance state opened singly and in bursts of several openings. 4. Mean open times of GABA receptor main conductance currents were increased and open‐time frequency histograms were shifted to longer times as GABA concentration was increased from 0.5 to 5 microM. Three exponential functions were required to fit the histograms at all GABA concentrations, suggesting that the channel opened into at least three open states (O1, O2 and O3). The three functions had the same time constants (1.0 +/‐ 0.2, 3.7 +/‐ 0.4 and 11.3 +/‐ 0.5 ms; mean +/‐ S.D.) at each concentration. The increase in long open times with concentration was due to a shift in relative frequency of occurrence of openings from the shortest (O1) to the two longest (O2 and O3) open states. 5. Closed‐time distributions of closures between main conductance state openings were fitted with multiple exponential functions, suggesting that the channel had several closed states. The two shortest time constants (0.24 +/‐ 0.03 and 2.0 +/‐ 0.3 ms) were concentration independent (0.5 to 5 microM). Three longer time constants decreased as concentration increased. 6. Bursts were defined as groups of openings surrounded by closures greater than a critical closed time (tc = 5 ms). Mean burst durations were increased and burst duration frequency histograms were shifted to longer times as GABA concentration was increased from 0.5 to 5 microM. Burst‐duration frequency histograms were best fitted with three exponential functions. The time constants were concentration independent and were 1.0 +/‐ 0.2, 5.5 +/‐ 0.2 and 29.8 +/‐ 1.6 ms. The increase in burst duration with concentration was due to a relative shift from short duration bursts to longer duration bursts. 7. The shortest burst time constant was similar to the shortest open time constant suggesting that there was a population of single openings of short duration. The two longest burst time constants were longer than the two longest open time constants, suggesting that the bursts from the two longest burst components were composed of two or more openings.(ABSTRACT TRUNCATED AT 400 WORDS)
影响因子：
5.5
作者：
JACKSON, MB
通讯作者：
JACKSON, MB