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在海龟视网膜视杆细胞中观察到的电压噪声。

Voltage noise observed in rods of the turtle retina.

作者信息

Schwartz E A

出版信息

J Physiol. 1977 Nov;272(2):217-46. doi: 10.1113/jphysiol.1977.sp012042.

Abstract
  1. Intracellular voltage was recorded from rods in isolated retinae of the snapping turtle, Chelydra serpentina. The voltage was observed during darkness or during uniform illumination of a large retinal area. During darkness the voltage fluctuated continuously about a mean level. The spontaneous fluctuation is termed ;noise'. During illumination the amplitude of the noise was reduced.2. The noise observed during darkness could also be reduced by injecting a hyperpolarizing current into the impaled rod. The noise could be increased by a depolarizing current. The component of the noise that could be altered by polarizing the rod is termed ;voltage-sensitive noise'.3. When voltage-sensitive noise was first minimized by a continuous hyperpolarizing current, bright light produced an additional decrease in the noise. The component of the noise that was eliminated by light, but not eliminated by the injection of current, is termed ;light-sensitive noise'.4. The power density spectrum of voltage-sensitive noise, G(v)(f), could be described by an equation of the form [Formula: see text] tau(M) was approximately 7 msec, which is in good agreement with an apparent membrane time constant of 5-8 msec. The largest value of alpha(v) was 2.1 x 10(-9) V(2) sec.5. The power density spectrum of light-sensitive noise could be described by an equation of the form [Formula: see text] tau(L) was approximately 200-300 msec. The largest value of alpha(L) was 8.0 x 10(-9) V(2) sec.6. The potential maintained during darkness could be altered by superfusing a retina with artificial media of different compositions. Depolarizing the rods by changing the extracellular calcium concentration from 1 to 5 mM increased the voltage-sensitive noise. A similar effect was observed after adding 2 mM lanthanum.7. In contrast, 5 mM cobalt produced a small hyperpolarization and suppressed the voltage-sensitive noise. Injecting a depolarizing current, after exposure to cobalt, re-initiated the voltage-sensitive noise. The ability to elicit voltage-sensitive noise in the presence of cobalt indicates that it was not of synaptic origin.8. The results are consistent with the noise present during dark being produced by two types of channel in the rod membrane. One is controlled by the phototransduction process; each individual channel of this type may be described as having a mean open time of 200-300 msec and a conductance of approx. 6 x 10(-13) Omega(-1). The absorption of one photon closes approx. 100-300 of these channels. The other type of channel is controlled by membrane potential; each individual channel of this type has a mean open time which is less than the membrane time constant of 8 msec.
摘要
  1. 从鳄龟(Chelydra serpentina)分离视网膜中的视杆细胞记录细胞内电压。在黑暗中或大面积视网膜均匀光照期间观察该电压。在黑暗中,电压围绕平均水平持续波动。这种自发波动被称为“噪声”。在光照期间,噪声幅度减小。

  2. 通过向刺入的视杆细胞注入超极化电流,也可降低黑暗中观察到的噪声。去极化电流可增加噪声。视杆细胞极化可改变的噪声成分被称为“电压敏感噪声”。

  3. 当通过连续超极化电流首先使电压敏感噪声最小化时,强光会使噪声进一步降低。被光消除但未被电流注入消除的噪声成分被称为“光敏感噪声”。

  4. 电压敏感噪声的功率密度谱G(v)(f),可用如下形式的方程描述:[公式:见原文]τ(M)约为7毫秒,这与5 - 8毫秒的表观膜时间常数非常吻合。α(v)的最大值为2.1×10⁻⁹V²秒。

  5. 光敏感噪声的功率密度谱可用如下形式的方程描述:[公式:见原文]τ(L)约为200 - 300毫秒。α(L)的最大值为8.0×10⁻⁹V²秒。

  6. 黑暗中维持的电位可通过用不同成分的人工介质灌注视网膜来改变。将细胞外钙浓度从1 mM变为5 mM使视杆细胞去极化,增加了电压敏感噪声。添加2 mM镧后观察到类似效果。

  7. 相反,5 mM钴产生小的超极化并抑制电压敏感噪声。暴露于钴后注入去极化电流,重新引发电压敏感噪声。在存在钴的情况下引发电压敏感噪声的能力表明它不是突触起源的。

  8. 结果与黑暗中存在的噪声由视杆细胞膜中的两种通道产生一致。一种由光转导过程控制;这种类型的每个单独通道可描述为平均开放时间为200 - 300毫秒,电导约为6×10⁻¹³Ω⁻¹。吸收一个光子会关闭约100 - 300个这些通道。另一种类型的通道由膜电位控制;这种类型的每个单独通道的平均开放时间小于8毫秒的膜时间常数。

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Analysis of electrical noise in turtle cones.龟视锥细胞电噪声分析。
J Physiol. 1977 Nov;272(2):435-68. doi: 10.1113/jphysiol.1977.sp012053.

引用本文的文献

本文引用的文献

1
Dark current and photocurrent in retinal rods.视网膜视杆细胞中的暗电流和光电流。
Biophys J. 1970 May;10(5):380-412. doi: 10.1016/S0006-3495(70)86308-1.
4
Responses of single rods in the retina of the turtle.乌龟视网膜中单个视杆细胞的反应。
J Physiol. 1973 Aug;232(3):503-14. doi: 10.1113/jphysiol.1973.sp010283.
5
Membrane noise.膜噪声
Prog Biophys Mol Biol. 1974;28:189-265. doi: 10.1016/0079-6107(74)90019-4.
10
Spontaneous voltage fluctuations in retinal cones and bipolar cells.
Nature. 1975 Aug 21;256(5519):661-2. doi: 10.1038/256661a0.

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