Electrotonic architecture of cat gamma motoneurons.
Electrotonic architecture of cat gamma motoneurons.
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猫伽玛运动神经元的电紧张结构。
DOI：
10.1152/jn.1994.72.5.2302
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发表时间：
1994
影响因子：
2.5
通讯作者：
Moschovakis,AK
中科院分区：
文献类型：
--
作者：
Burke,RE;Fyffe,RE;Moschovakis,AK
1.实验测量输入电阻，RN，和响应简短的超极化电流脉冲，获得在确定的γ-运动神经元在戊巴比妥麻醉猫使用传统的尖锐微量移液器。同样的细胞随后注射辣根过氧化物酶，并完全重建。在两个细胞中，电生理学和形态学数据的质量足以允许使用比细胞质电阻Ri和膜电容Cm的生物学合理范围来估计比膜电阻Rm。2.稳态和动态的计算机模型的组合被用来调和细胞形态与RN和短暂的电流脉冲传递到索马的电压衰减的轨迹。模拟瞬态响应匹配的尾部观察到的瞬态时，产生与实验使用的相同的电流注入。当Cm <或= 1.0 microF cm-2时，当分配给索马的Rm值Rms远小于分配给树突的空间均匀值Rmd且Ri = 60-70 Ω cm时，获得最令人满意的拟合。当Cm = 1.0 microF cm-2时，Rms的范围为260至427 Ω cm-2，而Rmd约为33 K Ω cm-2。当Cm = 0.8 microF cm-2时，Rms的范围为235至357 Ω cm 2，Rmd的范围为62至68 K Ω cm 2。当Rm被约束为空间均匀时（即，Rm = Rms），需要难以置信的高Cm值（2.5-5.0微F cm-2; Ri = 70 Ω cm）来匹配观察到的尾部时间常数τ 0，peel，但是模拟的瞬态与实验获得的瞬态不匹配。3.与最佳拟合值的RMS和RMD，两个γ-运动神经元电子相对紧凑（80%的总膜面积内的0.85长度常数从索马）。然而，计算出的树突内任何点产生的电压的平均稳态内向衰减因子（AFin）随着与索马的距离而迅速增加，在存在体细胞分流（Rms = Rmd）的情况下，相应运动神经元近端80%膜面积的AFin达到≤ 90和≤ 45的水平。如果我们假设体细胞分流是尖锐的微管穿透的伪影（即，未损伤细胞的Rms = Rmd），然后，对于近端80%的细胞膜，AFin分别降低至≤ 20和≤ 15。（400字处截断摘要）
1. Experimental measures of input resistance, RN, and responses to brief hyperpolarizing current pulses were obtained in identified gamma-motoneurons in pentobarbital-anesthetized cats using conventional sharp micropipettes. The same cells were subsequently injected with horseradish peroxidase and completely reconstructed. In two cells, the electrophysiological and morphological data were of sufficient quality to permit estimation of specific membrane resistance, Rm, using biologically plausible ranges of specific cytoplasmic resistance, Ri, and membrane capacitance, Cm. 2. A combination of steady-state and dynamic computer models were employed to reconcile cell morphology with RN and the trajectories of the voltage decay following brief current pulses delivered to the soma. Simulated transient responses matched the tails of the observed transient when generated with the same current injections used experimentally. With Cm < or = 1.0 microF cm-2, the most satisfactory fits were obtained when the values of Rm assigned to the soma, Rms, were much smaller than the spatially uniform value assigned to the dendrites, Rmd and Ri = 60–70 omega cm. With Cm = 1.0 microF cm-2, Rms ranged from 260 to 427 omega cm2, whereas Rmd was approximately 33 K omega cm2. With Cm = 0.8 microF cm-2, Rms ranged from 235 to 357 omega cm2 and Rmd was between 62 and 68 K omega cm2. When Rm was constrained to be spatially uniform (i.e., Rm = Rms), implausibly high values of Cm (2.5–5.0 microF cm-2; Ri = 70 omega cm) were required to match the observed tail time constant, tau o,peel, but the simulated transients did not otherwise match those obtained experimentally. 3. With best fit values of Rms and Rmd, both gamma-motoneurons were electronically relatively compact (80% of total membrane area within 0.85 length constants from the soma). However, the calculated average steady-state inward attenuation factor (AFin) for voltages generated at any point within the dendrites increased rapidly with distance from the soma, reaching levels of < or = 90 and < or = 45 for the proximal 80% of membrane area for the respective motoneurons in the presence of a somatic shunt (Rms ≪ Rmd). If we assume that the somatic shunt is an artifact of sharp micropipette penetration (i.e., that Rms = Rmd for uninjured cells), then AFin decreased to < or = 20 and < or = 15, respectively, for the proximal 80% of cell membrane.(ABSTRACT TRUNCATED AT 400 WORDS)