Dependence of Na-K pump current on internal Na+ in mammalian cardiac myocytes.
Dependence of Na-K pump current on internal Na+ in mammalian cardiac myocytes.
复制标题
哺乳动物心肌细胞中 Na-K 泵电流对内部 Na 的依赖性。
DOI：
10.1152/ajpheart.1990.259.2.h488
复制
发表时间：
1990
期刊：
影响因子：
--
通讯作者：
TenEick,RE
中科院分区：
文献类型：
--
作者：
Mogul,DJ;Singer,DH;TenEick,RE
Na-K泵电流（Ipump）是细胞内Na+浓度[（Na+]i）的函数。我们研究了定量关系Ipump和[Na+]i在离体豚鼠心室肌细胞在稳态条件下。[Na+]i用宽头吸管微电极控制和“钳位”在几个选定的浓度下，并用全细胞膜片电压钳技术测量膜电流。通过测量暴露于二氢哇巴因（1 mM）之前和期间稳态保持电流的变化来确定在-40 mV保持电位下产生的Ipump;在0至80 mM（n = 63）范围内的11个[Na+]i水平下测量Ipump，每个细胞仅测量一次，并归一化为细胞电容，以说明肌细胞间肌膜表面积的差异。Ipump表现出对[Na+]i的非线性依赖性;对该关系的Hill分析得出了泵刺激的半最大[Na+]i为43.2 mM，Hill系数为1.53。假设酶周转率需要Na+占据三个内部结合位点，对实验数据进行了替代分析。当仅假设两种不同的结合亲和力（KD）时，回归分析给出最佳拟合。值为KD 1 = 1 mM，KD 2 = KD 3 = 29 mM。根据使用后一模型的分析，Ipump饱和时的[Na+]i水平非常接近根据已发表的泵周转率和密度估计值计算的理论饱和水平。当内部[Na+]在正常静息生理水平范围内时，Na-K泵对[Na+]i变化的最大敏感性发生。
Na-K pump current (Ipump) is a function of the intracellular Na+ concentration [( Na+]i). We examined the quantitative relationship between Ipump and [Na+]i in isolated guinea pig ventricular myocytes under steady-state conditions. [Na+]i was controlled and "clamped" at several selected concentrations using wide-tipped pipette microelectrodes, and membrane current was measured using the whole cell patch voltage-clamp technique. Ipump generated at a holding potential of -40 mV was determined by measuring the change in steady-state holding current before and during exposure to dihydroouabain (1 mM); Ipump was measured at 11 levels of [Na+]i ranging from 0 to 80 mM (n = 63) with only one measurement per cell and normalized to cell capacitance to account for differences between myocytes in sarcolemmal surface area. Ipump exhibited a nonlinear dependence on [Na+]i; a Hill analysis of the relationship yielded a half-maximal [Na+]i for pump stimulation of 43.2 mM and a Hill coefficient of 1.53. An alternative analysis of the experimental data was performed assuming that occupation of three internal binding sites by Na+ is required for enzyme turnover. Regression analysis gave the best fit when only two different binding affinities (KD) are postulated. The values are KD1 = 1 mM, KD2 = KD3 = 29 mM. From the analysis using the latter model, the level of [Na+]i at which Ipump saturated closely approximated the theoretical saturation level calculated from published estimates of pump turnover rate and density. The maximal sensitivity of the Na-K pump to changes in [Na+]i occurs when internal [Na+] is within the range for the normal resting physiological level.
登录
查看更多内容
膳食蛋氨酸对大鼠亚硒酸盐和硒代蛋氨酸生物效力的影响。
DOI：
10.1093/jn/111.1.76
发表时间：
1981
期刊：
The Journal of nutrition
影响因子：
--
作者：
Sunde,RA;Gutzke,GE;Hoekstra,WG
通讯作者：
Hoekstra,WG
硒和维生素 E 缺乏对饲喂纯化饲料的绵羊的繁殖、生长、血液成分和组织损伤的影响。
DOI：
10.1093/jn/107.7.1288
发表时间：
1977
期刊：
The Journal of nutrition
影响因子：
--
作者：
P. Whanger;P. Weswig;J. A. Schmitz;J. Oldfield
通讯作者：
J. Oldfield
饲喂圆酵母饲料的大鼠在膳食肝坏死发展过程中的组织硒水平。
DOI：
10.1093/jn/95.3.420
发表时间：
1968
期刊：
The Journal of nutrition
影响因子：
--
作者：
R. Burk;R. Whitney;H. Frank;W. N. Pearson
通讯作者：
W. N. Pearson
人类、恒河猴、松鼠猴、大鼠和绵羊血液成分中硒和谷胱甘肽过氧化物酶的分布。
DOI：
10.1093/jn/113.11.2138
发表时间：
1983
期刊：
The Journal of nutrition
影响因子：
--
作者：
M. A. Beilstein;P. Whanger
通讯作者：
P. Whanger
亚硒酸盐、维生素E和N,N-二苯基对苯二胺对小鼠肝脏有机溶剂可溶性脂褐质色素的影响。
DOI：
10.1093/jn/114.9.1582
发表时间：
1984
期刊：
The Journal of nutrition
影响因子：
--
作者：
A. S. Csallany;L. Su;B. Z. Menken
通讯作者：
B. Z. Menken