Delayed rectifier outward K+ current is composed of two currents in guinea pig atrial cells.
Delayed rectifier outward K+ current is composed of two currents in guinea pig atrial cells.
复制标题
延迟整流器外向K电流由豚鼠心房细胞内的两个电流组成。
DOI：
--
复制
发表时间：
1991
影响因子：
--
通讯作者：
N. Jurkiewicz
中科院分区：
文献类型：
--
作者：
M. Sanguinetti;N. Jurkiewicz
用全细胞电压钳技术研究了豚鼠心房肌细胞延迟整流外向钾电流（IK）。类似于先前在心室细胞中的发现，心房细胞的IK是两个不同组分的复合物：IK，r，表现出强内向整流的快速激活电流和IK，s，仅具有适度整流的缓慢激活电流。IK，r由其对Co2+和III类抗肿瘤剂E-4031阻断的敏感性定义。IK，r是稳态电流-电压关系中突出的向外“驼峰”（在-30 mV和+40 mV之间）的基础。IK，r的激活不依赖于细胞内Ca ~（2+）浓度的瞬时变化。尼索地平或尼群地平阻断Ca ~（2+）电流不能阻止IK、r的激活。当细胞内Ca ~（2+）被1，2-双（氨基苯氧基）乙烷-N，N，N '，N'-四乙酸强缓冲时，细胞内的峰值IK，r不降低。心房细胞中IK，r的激活曲线的阈值为-40 mV，半值点为-19 mV，斜率因子为5.2 mV。IK，s的激活曲线的中点为+24 mV，斜率因子为15.7 mV。完全激活的IK，s（21.1pA/pF）和IK，r（2.53pA/pF）的峰值尾电流约为先前在豚鼠心室肌细胞中测量的两倍。这种电流密度的差异可以部分解释为什么豚鼠心脏心房细胞的动作电位比心室细胞的短。
The delayed rectifier outward K+ current (IK) was studied in isolated guinea pig atrial myocytes using the whole cell voltage-clamp technique. Similar to previous findings in ventricular cells, IK of atrial cells is the composite of two distinct components: IK,r, a rapidly activating current that exhibits strong inward rectification and IK,s, a slowly activating current with only modest rectification. IK,r was defined by its sensitivity to block by Co2+ and the class III antiarrhythmic agent, E-4031. IK,r underlies the prominent outward "hump" (between -30 and +40 mV) in the steady-state current-voltage relationship. Activation of IK,r was not dependent on transient changes in intracellular Ca2+ concentration. Block of Ca2+ current by nisoldipine or nitrendipine did not prevent activation of IK,r. Peak IK,r was not decreased in cells when intracellular Ca2+ was strongly buffered with 1,2-bis(aminophenoxy)ethane-N,N,N',N'-tetraacetic acid. The activation curve for IK,r in atrial cells had a threshold of -40 mV, a half-point of -19 mV, and a slope factor of 5.2 mV. The activation curve for IK,s had a half-point of +24 mV and a slope factor of 15.7 mV. The peak tail currents of fully activated IK,s (21.1 pA/pF) and IK,r (2.53 pA/pF) are about two times that previously measured in guinea pig ventricular cells. This difference in current density may partly explain why action potentials of atrial cells are shorter than those of ventricular cells in guinea pig hearts.