INTRACELLULAR CA2+ BUFFERS DISRUPT MUSCARINIC SUPPRESSION OF CA2+ CURRENT AND M-CURRENT IN RAT SYMPATHETIC NEURONS
INTRACELLULAR CA2+ BUFFERS DISRUPT MUSCARINIC SUPPRESSION OF CA2+ CURRENT AND M-CURRENT IN RAT SYMPATHETIC NEURONS
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DOI：
10.1073/pnas.88.2.652
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发表时间：
1991-01-01
影响因子：
11.1
通讯作者：
HILLE, B
中科院分区：
文献类型：
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作者：
BEECH, DJ;BERNHEIM, L;HILLE, B
利用全细胞膜片钳技术和fura-2荧光测量，研究了细胞内Ca2+浓度（[Ca2+]i）在分离的大鼠交感神经元中对Ca2+电流和m型K+电流的毒蕈碱抑制中的作用。毒蕈碱刺激抑制电流而不升高[Ca2+]i。然而，细胞内双（2-氨基苯氧基）乙烷-N，N，N‘，N’-四乙酸酯（BAPTA） （11-12 mM），一种Ca2+螯合剂，将Ca2+电流抑制从84%降低到46%，m型K+电流抑制从82%降低到15%。对于后者，我们解释了BAPTA的作用，需要一定的最小[Ca2+]i，才能继续运行将毒蕈碱受体连接到m型K+通道的途径。毒蕈碱受体与Ca通道的偶联途径也显示出一定的依赖性[Ca2+]i，但也可能存在独立于Ca2+螯合作用的BAPTA阻断作用。
The role of intracellular Ca2+ concentration ([Ca2+]i) in the muscarinic suppression of Ca2+ current and M-type K+ current has been investigated in isolated rat sympathetic neurons using the whole-cell patch-clamp technique and fura-2 fluorescence measurements. Muscarinic stimulation suppressed currents without raising [Ca2+]i. Nonetheless, intracellular bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetate (BAPTA) (11-12 mM), a Ca2+ chelator, reduced Ca2+-current suppression from 84 to 46% and M-type K+ current suppression from 82 to 15%. For the latter, we explain the BAPTA action by a requirement for a certain minimum [Ca2+]i for continued operation of the pathway coupling muscarinic receptors to M-type K+ channels. The pathway coupling muscarinic receptors to Ca channels also showed some dependence on [Ca2+]i, but there may also be a blocking action of BAPTA that is independent of Ca2+ chelation.