FAST, PERSISTENT, CA2(+) DEPENDENT K+ CURRENT CONTROLS GRADED ELECTRICAL-ACTIVITY IN CRAYFISH MUSCLE
FAST, PERSISTENT, CA2(+) DEPENDENT K+ CURRENT CONTROLS GRADED ELECTRICAL-ACTIVITY IN CRAYFISH MUSCLE
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DOI：
10.1007/bf00373891
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发表时间：
1995-08-01
影响因子：
4.5
通讯作者：
BUNO, W
中科院分区：
文献类型：
--
作者：
ARAQUE, A;BUNO, W
用双电极电压钳技术研究了克氏原螯虾肌纤维的早期外向电流。该电流在无Ca ~（2+）和5 mM Cd ~（2+）溶液中被消除，并被细胞外或细胞内四乙基铵阻断，表明它是一种Ca ~（2+）依赖性K ~+电流[I-K（Ca）]。I-K（ca）通道具有电压依赖性，对apamin不敏感，对Charybdotoxin（CTX）敏感，提示介导I-K（ca）的通道为BK型。I-K（Ca）激活非常快，在5 ms内达到最大值，失活不完全，稳定在持续的稳态。I-K（ca）对细胞内的乙撑双氧氮基四乙酸（EGTA）不敏感，但可被更快的钙离子螯合剂1，2-双（2-氨基苯氧基）乙烷-N，N，N '，N'-四乙酸（BAPTA）所消除，这表明电压依赖性钙通道和介导I-K（ca）的钙通道应该紧密地聚集在细胞膜上。在双电极电流钳记录模式下，低幅度，梯度反应，在控制条件下引起的，而重复的所有或没有尖峰引起的应用程序的CTX或加载后的细胞与BAPTA。我们的结论是，I-K（CA）激活非常迅速：是持久的，是负责的低振幅，分级，主动响应的开放肌纤维的生成和控制。
The early outward current in opener muscle fibres of crayfish (Procambarus clarkii) was studied using the two-electrode voltage-clamp technique. This current was abolished in Ca2+-free and 5 mM Cd2+ solutions, and was blocked by extra- or intracellular tetraethylammonium, indicating that it was a Ca2+-dependent K+ current [I-K(Ca)]. I-K(ca) was voltage dependent, apamin insensitive and sensitive to charybdotoxin (CTX), which, in addition to its tetraethylammonium sensitivity, suggests that the channels mediating I-K(ca) behave in a BK type manner. I-K(ca) activation was extremely fast, reaching a maximum within 5 ms, and the inactivation was incomplete, stabilizing at a persistent steady-state. I-K(ca) was insensitive to intracellular ethylenebis(oxonitrilo)tetraacetate (EGTA), but was abolished by injection of the faster Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), suggesting that voltage-dependent Ca2+ channels and those mediating I-K(ca), should be clustered closely on the membrane. Under two-electrode current-clamp recording mode, low amplitude, graded responses were evoked under control conditions, whereas repetitive all-or-none spikes were elicited by application of CTX or after loading the cells with BAPTA. We conclude that I-K(ca) activates extremely quickly: is persistent and is responsible for the generation and control of the low amplitude, graded, active responses of opener muscle fibres.