Mechanism of staurosporine-induced decrease in acetylcholine receptor recovery from desensitization.
Mechanism of staurosporine-induced decrease in acetylcholine receptor recovery from desensitization.
复制标题
星形孢菌素诱导乙酰胆碱受体脱敏恢复下降的机制。
DOI：
10.1111/j.1476-5381.1993.tb12871.x
复制
发表时间：
1993
影响因子：
7.3
通讯作者：
Parsons,RL
中科院分区：
文献类型：
--
作者：
Hardwick,JC;Parsons,RL
1之前，我们在电压钳位蛇颤肌纤维中发现，通过蛋白激酶抑制剂staurosporine预处理，烟碱乙酰胆碱（ACh）受体从卡巴胆碱诱导的脱敏中恢复的程度降低。本研究旨在确定星形孢菌素诱导的恢复抑制的潜在机制。2用0.5 μ m星形孢菌素预处理显著降低自发性微终板电流（m.e.p.c.）暴露于540 μmcarbachol的制剂中的振幅。m.e.p.c.恢复率下降。星形孢菌素的振幅依赖于卡巴胆碱暴露的持续时间。m.e.p.c.无显著降低。激动剂暴露1 min时观察到振幅，而激动剂暴露5-10 min时观察到恢复显著降低。此外，星形孢菌素预处理对ACh受体恢复的影响是持久的，使得m.e.p.c.振幅保持降低至少60 min。3在20 μ m卡巴胆碱局部灌注期间通过噪声分析估计平均通道电导，表明在从脱敏恢复后，星形孢菌素处理的制剂中电导从52 pS降低至23 pS。在不存在脱敏的情况下，星形孢菌素处理没有改变平均通道电导。4在对照和未暴露于卡巴胆碱的星形孢菌素处理的制剂中，在酶清洁终板的细胞附着斑中记录了电导为45-49 pS的ACh激活单通道电流的单个群体。5在暴露于卡巴胆碱的星形孢菌素处理的终板中，然后允许恢复，观察到一群小电导（23 pS）通道。这些通道在经历了卡巴胆碱诱导的脱敏和恢复的对照制剂中通常看不到。在星形孢菌素处理的终板中从脱敏恢复后观察到的振幅是由小电导和大电导ACh受体通道的混合物的激活引起的。
1Previously, we showed in voltage‐clamped snake twitch muscle fibres that the extent of recovery of the nicotinic acetylcholine (ACh) receptor from carbachol‐induced desensitization is reduced by pretreatment with the protein kinase inhibitor staurosporine. The present studies were undertaken to determine the mechanism underlying the staurosporine‐induced inhibition of recovery.2Pretreatment with 0.5 μmstaurosporine significantly decreased the extent of recovery of spontaneous miniature endplate current (m.e.p.c.) amplitudes in preparations exposed to 540 μmcarbachol. The decrease in recovery of m.e.p.c. amplitude by staurosporine was dependent on the duration of carbachol exposure. No significant decrease in m.e.p.c. amplitude was observed with a 1 min exposure to agonist, whereas a significant decrease in recovery was seen with agonist exposures between 5–10 min. Further, the effect of staurosporine pretreatment on ACh receptor recovery was long‐lasting such that m.e.p.c. amplitude remained decreased for at least 60 min.3Estimation of mean channel conductance by noise analysis during local perfusion of 20 μmcarbachol demonstrated a decrease in conductance from 52 pS to 23 pS in staurosporine‐treated preparations following recovery from desensitization. Staurosporine treatment in the absence of desensitization did not alter the mean channel conductance.4A single population of ACh‐activated single channel currents with a conductance of 45–49 pS was recorded in cell‐attached patches from enzymatically cleaned endplates in control and staurosporine‐treated preparations not exposed to carbachol.5At staurosporine‐treated endplates exposed to carbachol and then allowed to recover, a population of small conductance (23 pS) channels was observed. These channels were not normally seen in control preparations which had undergone carbachol‐induced desensitization and recovery.6We suggest that the decrease in m.e.p.c. amplitude observed following recovery from desensitization in staurosporine‐treated endplates results from the activation of a mixture of small and large conductance ACh receptor channels.