Outward Potassium Currents in Freshly Isolated Smooth Muscle Cell of Dog Coronary Arteries
Outward Potassium Currents in Freshly Isolated Smooth Muscle Cell of Dog Coronary Arteries
复制标题
新鲜分离的狗冠状动脉平滑肌细胞的外向钾电流
作者：
D. W. Wilde;K. Lee
在成年比格犬的单个冠状动脉平滑肌细胞中表征了外膜电流。细胞的平均值为96.4×7.1 fim，静息电位为−50.7 mV，输入电阻为307.9 MΩ，电容为323 pF，计算的膜表面积为4，037 μm2。细胞对外加乙酰胆碱或高K+反应性收缩。用吸管法进行电压钳时，在-50 mV时开始出现外向电流，50 mV时达到15.2 nA，电流密度为376.5 μA/cm 2。电流被外部的四乙基铵、Ba ~（2+）和内部的Cs ~+所抑制，其反转电位与外部的K ~+浓度呈能斯特关系。将外部Ca 2+（Ca 2 + 0）从0升高至0.3 mM可使总K+电流增加300%;通过内部灌注将内部Ca 2+（Ca 2 + 1）升高至5×10−7 M可使总外向电流增加相似程度，表明Ca 2+跨膜敏感性存在较大差异。总的全细胞K+电流由两个部分组成：初始的时间无关性电流（Ii），随后是时间依赖性电流（It）。Ii和It通过不同的K+通道，其差异基于a）对Ca 2 + O的敏感性，B）内向Ca 2+电流的调节，c）电流幅度和激活动力学，以及d）对药理学试剂的反应。I是最大的组分，在0 mM Ca 2 + O中测得4.5 nA，但在03 mM Ca 2 + O中增加到11.9 nA，具有陡峭的2.5幂函数。它的激活与双指数的时间过程中，在Ca 2 + 0-免费的解决方案，其时间过程是相对不敏感的电压变化，但成为电压敏感的Ca 2 + 0的存在下。此外，这种敏感性被消除或增强由Co 2 * 或Bay K 8644，分别。我们的结论是，有两种类型的钙敏感的K+电流，锂和它，在冠状动脉平滑肌细胞。通过内向的Ca 2+通道，Ca 2 + 0在幅度和动力学上强烈调节它。
Outward membrane currents were characterized in single coronary smooth muscle cells of adult beagle dogs. The cells averaged 96.4×7.1 fim and had a resting potential of −50.7 mV, an input resistance of 307.9 MΩ, a capacitance of 323 pF, and a calculated membrane surface area of 4,037 μm2. The cells contracted in response to external application of acetylcholine or high K+. In voltage clamp by use of the suction pipette method, outward current began to appear at -50 mV and reached 15.2 nA at 50 mV with a current density of 376.5 μA/cm2. The current was reduced by external tetraethylammonium, Ba2+, and internal Cs+, and its reversal potential had a Nernst relation to external K+ concentration. Elevation of external Ca2+ (Ca2+ 0) from 0 to 0.3 mM increased total K+ current by up to 300%; elevation of internal Ca2+ (Ca2+,) to 5×10−7 M by internal perfusion increased total outward current to a similar extent, suggesting a large difference in Ca2+ transmembrane sensitivity. Total whole-cell K+ current consisted of two components: an initial time-independent current (Ii) followed by a time-dependent current (It. Ii and It were through separate K+ channels based on differences in a) sensitivity to Ca2+ O, b) modulation by an inward Ca2+ current, c) current amplitudes and activation kinetics, and d) responses to pharmacological agents. I, was the largest component, measuring 4.5 nA in 0 mM Ca o but increasing to 11.9 nA in 03 mM Ca2+ O with a steep 2.5 power function. It activated with a biexponential time course; in Ca2+ o-free solution, its time course was relatively insensitive to voltage changes but became voltage sensitive in the presence of Ca2+ 0. Further, such sensitivity was abolished or enhanced by Co2* or Bay K 8644, respectively. We concluded that there are two types of Ca2+-sensitive K+ currents, li and It, in coronary smooth muscle cells. Via an inward Ca2+ channel Ca2+ 0 strongly modulates It, both in amplitude and kinetics.
登录
查看更多内容
新鲜分离的平滑肌细胞中大电导 Ca2 激活的 K 通道。
DOI：
10.3109/09687688609065445
发表时间：
1986
期刊：
Membrane biochemistry
影响因子：
--
作者：
Singer,JJ;WalshJr,JV
通讯作者：
WalshJr,JV
单个平滑肌细胞出现螺旋状缩短。
DOI：
10.1126/science.3109034
发表时间：
1987
期刊：
Science (New York, N.Y.)
影响因子：
--
作者：
Warshaw,DM;McBride,WJ;Work,SS
通讯作者：
Work,SS
单个新鲜分离的平滑肌细胞膜的被动特性。
DOI：
10.1152/ajpcell.1980.239.5.c153
发表时间：
1980
期刊：
The American journal of physiology
影响因子：
--
作者：
Singer,JJ;WalshJr,JV
通讯作者：
WalshJr,JV
兔门静脉单个平滑肌细胞中的宏观 K 电流。
DOI：
10.1113/jphysiol.1989.sp017641
发表时间：
1989
期刊：
The Journal of physiology
影响因子：
--
作者：
Hume,JR;Leblanc,N
通讯作者：
Leblanc,N