星形孢菌素诱导脱敏的乙酰胆碱受体恢复能力降低的机制。

Mechanism of staurosporine-induced decrease in acetylcholine receptor recovery from desensitization.

作者信息

Hardwick J C, Parsons R L

机构信息

Department of Anatomy and Neurobiology, University of Vermont, Burlington 05405.

出版信息

Br J Pharmacol. 1993 Mar;108(3):741-8. doi: 10.1111/j.1476-5381.1993.tb12871.x.

DOI:10.1111/j.1476-5381.1993.tb12871.x

PMID:7682136

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC1908029/

Abstract

Previously, 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. 2. Pretreatment with 0.5 microM staurosporine significantly decreased the extent of recovery of spontaneous miniature endplate current (m.e.p.c.) amplitudes in preparations exposed to 540 microM carbachol. 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. 3. Estimation of mean channel conductance by noise analysis during local perfusion of 20 microM carbachol 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. 4. A 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. 5. At 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.6. We 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.

摘要

此前，我们在电压钳制的蛇类抽搐肌纤维中发现，用蛋白激酶抑制剂星形孢菌素预处理会降低烟碱型乙酰胆碱（ACh）受体从卡巴胆碱诱导的脱敏状态恢复的程度。本研究旨在确定星形孢菌素诱导抑制恢复的潜在机制。2. 用0.5微摩尔/升星形孢菌素预处理显著降低了暴露于540微摩尔/升卡巴胆碱的标本中自发微小终板电流（m.e.p.c.）幅度的恢复程度。星形孢菌素导致的m.e.p.c.幅度恢复降低取决于卡巴胆碱暴露的持续时间。暴露于激动剂1分钟时，未观察到m.e.p.c.幅度有显著降低，而暴露于激动剂5 - 10分钟时，恢复有显著降低。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.幅度至少60分钟内仍保持降低。3. 在局部灌注20微摩尔/升卡巴胆碱期间通过噪声分析估计平均通道电导，结果显示脱敏恢复后，星形孢菌素处理的标本中电导从52皮西门子降至23皮西门子。在未脱敏的情况下进行星形孢菌素处理不会改变平均通道电导。4. 在对照和未暴露于卡巴胆碱的星形孢菌素处理的标本中，从酶解清洁的终板的细胞贴附片中记录到单一群落的ACh激活的单通道电流，其电导为45 - 49皮西门子。5. 在暴露于卡巴胆碱然后恢复的星形孢菌素处理的终板处，观察到一群小电导（23皮西门子）通道。在经历卡巴胆碱诱导的脱敏和恢复的对照标本中通常看不到这些通道。6. 我们认为，在星形孢菌素处理的终板中，脱敏恢复后观察到的m.e.p.c.幅度降低是由小电导和大电导ACh受体通道混合物的激活所致。