HETEROGENEOUS KINETIC-PROPERTIES OF ACETYLCHOLINE-RECEPTOR CHANNELS IN XENOPUS MYOCYTES
HETEROGENEOUS KINETIC-PROPERTIES OF ACETYLCHOLINE-RECEPTOR CHANNELS IN XENOPUS MYOCYTES
复制标题
DOI：
10.1113/jphysiol.1986.sp016211
复制
发表时间：
1986-09-01
影响因子：
5.5
通讯作者：
LINGLE, CJ
中科院分区：
文献类型：
--
作者：
AUERBACH, A;LINGLE, CJ
1.我们用细胞贴附式膜片钳技术研究了非洲爪蟾心肌细胞乙酰胆碱受体通道电流的动力学和电导特性。2.在高激动剂浓度（5-100 μ M）下，电流出现在开口的爆发中。通道在爆发期间以离子传导构象存在的概率（Po）被采用作为通道动力学行为的经验测量。3.给定脉冲群内的所有开口均具有相同的平均电流幅度。然而，不同的脉冲串可以具有平均电导为46 pS（γ 40）或64 pS（γ 60）的开口。4.对于γ 40爆发，存在三个主要群体，其可以通过它们的平均Po值（约0.9，约在20 μ M-乙酰胆碱时<0.3和< 0.01）。Po值随着微量移液器内乙酰胆碱浓度的增加而增加。大约80%的爆发来自最高的Po种群。5.γ 60爆发也发生在三种主要模式中。最高的Po群体占所有爆发的> 80%，并且具有约0.4的平均Po。0.6 20 μ M-乙酰胆碱。6.对于γ 40和γ 60通道，来自最高Po群的脉冲串具有约为λ的开放间隔持续时间。4倍以上，从爆发从中等Po人口。从γ 40开始的闭合间隔，高Po爆发为约比中等波力爆发短4倍。7.偶尔的例子之间切换不同的动力学模式进行了观察，这表明Po人口可能代表不同的活动模式的一个均匀的通道人口。
1. We have used the cell-attached patch-clamp technique to examine the kinetic and conductance properties of acetylcholine receptor channel currents in cultured Xenopus myocytes. 2. At high agonist concentrations (5-100 .mu.M) the currents occurred in bursts of openings. The probability that a channel existed in an ion-conducting conformation during a burst (Po) was adopted as an empirical measure of channel kinetic behaviour. 3. All openings within a given burst were to the same mean current amplitude. However, different bursts could have openings with a mean conductance of either 46 pS (.gamma.40) or 64 pS (.gamma.60). 4. For .gamma.40 bursts there were three predominant populations which could be distinguished by their mean Po values (.apprx. 0.9, .apprx. 0.3, and < 0.01 at 20 .mu.M-acetylcholine). Po values increased as the acetylcholine concentration within the micropipette was increased. About 80% of bursts were from the highest Po population. 5. .gamma.60 bursts also occurred in three predominant modes. The highest Po population accounted for > 80% of all bursts and had a mean Po of .apprx. 0.6 at 20 .mu.M-acetylcholine. 6. For both .gamma.40 and .gamma.60 channels, bursts from the highest Po population had open-interval durations which were .apprx. 4 times longer than those from bursts from the medium Po population. Closed intervals from .gamma.40, high Po bursts were .apprx. 4 times shorter than those from medium Po bursts. 7. Occasional examples of switching between different kinetic modes were observed, suggesting that the Po population may represent different activity patterns of a homogeneous channel population.