Activation of single ion channels from toad retinal rod inner segments by cyclic GMP: concentration dependence.
Activation of single ion channels from toad retinal rod inner segments by cyclic GMP: concentration dependence.
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环 GMP 激活蟾蜍视网膜杆内节的单离子通道：浓度依赖性。
DOI：
10.1113/jphysiol.1988.sp017255
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发表时间：
1988
期刊：
影响因子：
--
通讯作者：
Watanabe,S
中科院分区：
文献类型：
--
作者：
Matthews,G;Watanabe,S
1. 膜片钳记录来自蟾蜍杆光感受器的单环 GMP 激活通道，是在仅包含一个这样的通道的由内而外的膜片中进行的。补片是从内部段获得的，其中循环 GMP 激活通道的密度低于外部段，使得单通道补片成为可能。研究了通道门控对环 GMP 浓度 ([环 GMP]) 的依赖性。在低[环 GMP]（5-10 µM）下，通道打开不频繁，并且以快速打开和关闭的爆发形式发生。随着[环状 GMP] 的增加，爆发变得更加频繁，直到 1 mM 时，活动融合成打开和关闭状态之间的长时间快速闪烁。 2. 突发中短暂打开和关闭（闪烁）的持续时间不受[循环GMP]影响。这表明突发内的快速闪烁是由与激动剂诱导的受体激活无关的内在通道特性引起的。 3. 在 10 microM 循环 GMP 下，闭合时间的分布由三个指数分量之和拟合。最短的部分（时间常数平均为 0.29 毫秒）对应于突发内的短暂关闭，而两个较长的组件（时间常数平均为 3.5 和 32 毫秒）对应于突发之间更长的关闭时间。在 0.5 或 1 mM 环状 GMP（饱和度）下，较长的成分消失，并且闭合时间的分布通过单指数方程拟合，其时间常数与在较低浓度下观察到的最短成分相同。 4. 由于即使在高[循环 GMP] 下通道也会继续闪烁，因此处于打开状态 (Po) 的最大概率没有接近 1.0，平均为 0.30 +/- 0.05 (N = 8)。 Po 和[环 GMP] 之间的关系由指数为 3 的 Hill 方程拟合，表明需要环 GMP 与多个位点结合才能打开通道。
1. Patch‐clamp recordings of single cyclic GMP‐activated channels from toad rod photoreceptors were made in inside‐out membrane patches containing only one such channel. Patches were obtained from the inner segment, where the density of cyclic GMP‐activated channels is lower than in the outer segment, making one‐channel patches possible. The dependence of channel gating on cyclic GMP concentration ([cyclic GMP]) was studied. At low [cyclic GMP] (5‐10 microM), channel openings were infrequent and occurred as bursts of rapid opening and closing. As [cyclic GMP] was increased, bursts became more frequent, until at 1 mM the activity fused into long bouts of rapid flicker between open and closed states. 2. The duration of brief openings and closings (flicker) within bursts was not affected by [cyclic GMP]. This suggests that the rapid flicker within bursts results from an intrinsic channel property not associated with agonist‐induced receptor activation. 3. At 10 microM‐cyclic GMP, the distribution of closed times was fitted by a sum of three exponential components. The briefest, with time constant averaging 0.29 ms, corresponded to the brief closings within bursts, while the two longer components, with time constants averaging 3.5 and 32 ms, corresponded to much longer closings between bursts. At 0.5 or 1 mM‐cyclic GMP (saturation), the longer components disappeared, and the distribution of closed times was fitted by a single‐exponential equation with the same time constant as the briefest component observed at lower concentrations. 4. Because the channel continued to flicker even at high [cyclic GMP], the maximal probability of being in the open state (Po) did not approach 1.0, averaging 0.30 +/‐ 0.05 (N = 8). The relation between Po and [cyclic GMP] was fitted by the Hill equation with an exponent of 3, suggesting that binding of cyclic GMP to multiple sites is required to open the channel.
影响因子：
64.8
作者：
HAYNES, LW;KAY, AR;YAU, KW
通讯作者：
YAU, KW
单通道记录表明 cGMP 打开视杆光感受器的光敏离子通道。
DOI：
10.1073/pnas.84.1.299
发表时间：
1987
影响因子：
11.1
作者：
Matthews,G
通讯作者：
Matthews,G
影响因子：
1.8
作者：
D. Baylor;T. Lamb;K. Yau
通讯作者：
K. Yau