SODIUM UPTAKE AND MEMBRANE EXCITATION IN PARAMECIUM
SODIUM UPTAKE AND MEMBRANE EXCITATION IN PARAMECIUM
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DOI：
10.1083/jcb.81.2.374
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发表时间：
1979-01-01
影响因子：
7.8
通讯作者：
HANSMA, HG
中科院分区：
文献类型：
--
作者：
HANSMA, HG
虽然许多P. tetraurelia的膜激发突变体的表型在含Na+的溶液中最好地表达，但对Na+在草履虫膜激发中的作用知之甚少。基于测量22 Na通量，如果Na+浓度在整个细胞中是均匀的，则总细胞Na+含量相当于3-4 mM的细胞质浓度。Na+吸收的动力学可以分为饱和Na+吸收与表观Km = 0.15 mM和非饱和Na+吸收看到在较高的Na+浓度高达20 mM。Na+吸收率在高Na+溶液中与野生型草履虫和突变体快速-2和偏执狂的向后游泳和膜兴奋的持续时间相关。Na+摄取在4.0 ℃时受到抑制。C. Na+摄取可能更快时，膜去极化比当它是在静息电位水平。
Although the phenotypes of many membrane-excitation mutants of P. tetraurelia are best expressed in Na+-containing solutions, little is known about the role of Na+ in membrane excitation in Paramecium. Based on measuring 22Na fluxes, the total cellular Na+ content is equivalent to a cytoplasmic concentration of 3-4 mM, if the Na+ concentration is uniform throughout the cell. The kinetics of Na+ uptake can be divided into a saturable Na+ uptake with an apparent Km = 0.15 mM and a nonsaturable Na+ uptake seen at higher Na+ concentrations up to 20 mM. The rate of Na+ uptake in high Na+ solutions is correlated with the duration of backward swimming and membrane excitation in wild type Paramecium and the mutants fast-2 and paranoiac. Na+ uptake is inhibited at 4.degree. C. Na+ uptake may be faster when the membrane is depolarized than when it is at the resting potential level.