分离的蜗牛神经元中乙酰胆碱诱导的氯离子电流的动力学分析。

Kinetic analysis of acetylcholine-induced chloride current in isolated snail neurons.

作者信息

Ikemoto Y, Ishizuka S, Ono K, Akaike N

机构信息

Department of Physiology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.

出版信息

Cell Mol Neurobiol. 1988 Sep;8(3):293-305. doi: 10.1007/BF00711171.

DOI:10.1007/BF00711171

PMID:3224358

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC11567629/

Abstract

Kinetics of activation and desensitization phases of the acetylcholine (ACh)-induced chloride current (ICI) were studied using isolated single neurons of Japanese land snail and the "concentration clamp" technique. 2. The dose-response curve for the peak ICI gave a dissociation constant of 7.1 x 10(-6) M and a Hill coefficient of 1.8. 3. The current-voltage relationship was linear in the voltage range examined (-60 to +10 mV) and the reversal potential (EACh) was -7.2 +/- 1.5 mV (N = 10). The value was close to the calculated equilibrium potential for chloride ions (ECI). 4. Both activation and desensitization phases of the ACh-induced ICI consisted of a single exponential at concentrations less than 3 x 10(-6) M and a double exponential at higher concentrations. The time constants of both phases decreased with increasing ACh concentrations but showed no potential dependency. 5. The recovery from desensitization of the ICI induced by 5 x 10(-6) M ACh proceeded double exponentially, with time constants of 11 and 114 sec at a holding potential of -30 mV. 6. Noise analysis was performed on a steady-state current induced by 3 x 10(-7) to 2 x 10(-6) M ACh. The mean open time was about 60 msec at 10(-6) M ACh and the single-channel conductance was 14 PS. 7. These results suggest that the ACh receptor-Cl channel complex in snail neurons has two binding sites with the dissociation constant of 7.1 x 10(-6) M and is rapidly activated and desensitized to a steady level in the presence of the agonist.

摘要

利用日本陆地蜗牛的分离单神经元和“浓度钳”技术，研究了乙酰胆碱（ACh）诱导的氯离子电流（ICI）的激活和脱敏阶段的动力学。2. 峰值ICI的剂量反应曲线给出的解离常数为7.1×10⁻⁶ M，希尔系数为1.8。3. 在检测的电压范围（-60至+10 mV）内，电流-电压关系呈线性，反转电位（EACh）为-7.2±1.5 mV（N = 10）。该值接近计算出的氯离子平衡电位（ECI）。4. ACh诱导的ICI的激活和脱敏阶段在浓度低于3×10⁻⁶ M时均由单指数组成，在较高浓度时由双指数组成。两个阶段的时间常数均随ACh浓度增加而降低，但无电位依赖性。5. 由5×10⁻⁶ M ACh诱导的ICI脱敏后的恢复呈双指数进行，在-30 mV的保持电位下，时间常数分别为11和114秒。6. 对由3×10⁻⁷至2×10⁻⁶ M ACh诱导的稳态电流进行了噪声分析。在10⁻⁶ M ACh时，平均开放时间约为60毫秒，单通道电导为14 pS。7. 这些结果表明，蜗牛神经元中的ACh受体-Cl通道复合物有两个结合位点，解离常数为7.1×10⁻⁶ M，在激动剂存在下能迅速激活并脱敏至稳定水平。