Electrogenic K+ transport by the Na+–K+ pump in rat cardiac ventricular myocytes
Electrogenic K+ transport by the Na+–K+ pump in rat cardiac ventricular myocytes
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大鼠心室肌细胞中 Na+–K+ 泵的电动 K+ 转运
DOI：
10.1111/j.1469-7793.1997.033bo.x
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
J. Berlin
中科院分区：
文献类型：
--
作者：
R. D. Peluffo;J. Berlin
1采用全细胞膜片钳技术，测定了大鼠心室肌细胞Na+，K+-ATP酶参与K+转运的生电反应步骤。2在K+-K+交换条件下，以及存在刺激亚最大水平稳态Na+、K+-ATP酶活性的浓度的细胞外K+或TI+的情况下，在（“开”）和（“关”）期间观察到哇巴因敏感的瞬时电流膜电位（Vm）的阶跃变化。[3]在瞬态电流期间移动的电荷量以可饱和的方式取决于电压阶跃的幅度。哇巴因敏感的最大“开”和“关”电荷分别计算为9.6 ± 0.9和9.1 ± 0.4 fC pF−1（n= 4），有效化合价为0.48 ± 0.07（n= 7）。4在正电位下，瞬态电流的动力学与Vm和Tlo+无关，但在Vm值越来越负时，以离子浓度依赖性方式变得更快。5这些数据表明，产电步骤参与Na+，K+-ATP酶的K+转运，并且产电步骤是细胞外离子结合。6在K+-K+和Na+-Na+交换条件下比较了瞬态电荷运动的温度和Vm依赖性。这些数据表明，细胞外的K+和Na+结合发生在不同的网站中的酶或不同的酶构象。有效化合价之和为1.14 ± 0.12，表明细胞外离子结合的产电性可以解释Na+，K+-ATP酶的离子转运的Vm依赖性。
1 The involvement of electrogenic reaction steps in K+ transport by the Na+,K+‐ATPase was determined in rat cardiac ventricular myocytes using whole‐cell patch clamp techniques. 2 Under K+–K+ exchange conditions and in the presence of extracellular K+ or Tl+ at concentrations that stimulated submaximal levels of steady‐state Na+,K+‐ATPase activity, ouabain‐sensitive transient currents were observed during (‘on’) and after (‘off’) step changes in membrane potential (Vm). 3 The quantity of charge moved during the transient currents depended, in a saturable manner, on the magnitude of the voltage step. Maximal ouabain‐sensitive ‘on’ and ‘off’ charges were calculated to be 9.6 ± 0.9 and 9.1 ± 0.4 fC pF−1 (n= 4), respectively, with an effective valency of 0.48 ± 0.07 (n= 7). 4 Kinetics of the transient currents were independent of Vm and Tlo+ at positive potentials, but became more rapid at increasingly negative Vm values in an ion concentration‐dependent fashion. 5 These data demonstrate that electrogenic steps participate in K+ transport by the Na+,K+‐ATPase and that the electrogenic step is extracellular ion binding. 6 The temperature‐and Vm‐dependent properties of transient charge movements were compared under K+–K+ and Na+–Na+ exchange conditions. The data suggest that extracellular K+ and Na+ binding occur at different sites in the enzyme or to different enzyme conformations. The sum of the effective valencies, 1.14 ± 0.12, demonstrates that the electrogenicity of extracellular ion binding can explain the Vm dependence of ion transport by the Na+,K+‐ATPase.
影响因子：
56.9
作者：
GADSBY, DC;RAKOWSKI, RF;DEWEER, P
通讯作者：
DEWEER, P
肌细胞中瞬态和稳态 Na/K 泵电流的电压依赖性。
影响因子：
4.3
作者：
Gadsby,DC;Nakao,M;Bahinski,A
通讯作者：
Bahinski,A
磷酸盐抑制人红细胞钠泵：三磷酸腺苷和磷酸盐同时结合。
DOI：
10.1113/jphysiol.1988.sp017136
发表时间：
1988
期刊：
The Journal of physiology
影响因子：
--
作者：
Sachs,JR
通讯作者：
Sachs,JR