Two‐component desensitization of nicotinic receptors induced by acetylcholine agonists in Lymnaea stagnalis neurones.
Two‐component desensitization of nicotinic receptors induced by acetylcholine agonists in Lymnaea stagnalis neurones.
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停滞 Lymnaea stagnalis 神经元中乙酰胆碱激动剂诱导烟碱受体的双组分脱敏。
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发表时间：
1984
期刊：
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通讯作者：
C. Vulfius
中科院分区：
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作者：
A. A. Andreev;B. N. Veprintsev;C. Vulfius
利用电压箝位技术，研究了不同乙酰胆碱激动剂诱导的脱敏动力学以及脱敏后的恢复动力学。脱敏遵循两个指数的总和：一个快，一个慢。在室温（18 ~ 23℃）下，ACh应用下的快速脱敏组分（tau id）的时间常数在秒范围内。它在冷却时增加（Q10 = 2.8 +/‐0.9），随着ACh浓度的增加而降低，并且与膜电压无关。增敏慢分量的时间常数在几十秒的范围内。它随着药物浓度的增加而降低，与温度的依赖性较弱（Q10 = 1.3 +/‐0.4）。快速分量的相对振幅，通过反向外推估计到峰值电流的位置，随着激动剂浓度的增加而增加，随着冷却而减少。脱敏恢复遵循两个指数的和，时间常数（tau Ir和tau IIr）分别为秒和分的数量级。冷却延长了tau IIr的慢速组分（Q10）。3)并减少其在恢复过程中的贡献。对各种激动剂诱导的脱敏反应的比较表明，对于小的单季激动剂，脱敏的开始和恢复与乙酰胆碱的开始和恢复相似。对于体积更大的激动剂，如乙氧基脂酰胆碱、脂酰胆碱和亚胆碱，在长时间应用激动剂期间，反应的衰减可能涉及额外的阻断过程。
The kinetics of desensitization induced by different agonists of acetylcholine (ACh) as well as the kinetics of recovery from densensitization, have been studied using the voltage‐clamp technique in isolated, identified Lymnaea stagnalis neurones. Desensitization follows the sum of two exponentials: one fast and one slow. The time constant of the fast desensitization component (tau Ids) under ACh application is in the range of seconds at room temperature (18‐23 degrees C). It increases upon cooling (Q10 = 2.8 +/‐ 0.9), decreases with increasing ACh concentration and is independent of membrane voltage. The time constant of the slow component of densensitization (tau Ids) is in the range of tens of seconds. It decreases with increasing drug concentration and is weakly dependent upon temperature (Q10 = 1.3 +/‐ 0.4). The relative amplitude of the fast component, estimated by back extrapolation to the position of the peak current, increases with agonist concentration and decreases upon cooling. Recovery from desensitization follows the sum of two exponentials with time constants (tau Ir and tau IIr) of the order of seconds and minutes, respectively. Cooling prolongs the slow component (Q10 of tau IIr is approx. 3) and reduces its contribution during recovery. A comparison of the desensitization induced by various agonists indicates that for the small monoquaternary agonists the onset and recovery of desensitization resemble the onset and recovery observed with ACh. For more bulky agonists, like ethoxysebacylcholine, sebacylcholine and suberylcholine, the decay of the response during prolonged application of the agonist may involve an additional blocking process.