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首页> 美国卫生研究院文献>The Journal of General Physiology >Reflection coefficient and permeability of urea and ethylene glycol in the human red cell membrane
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Reflection coefficient and permeability of urea and ethylene glycol in the human red cell membrane

机译：尿素和乙二醇在人红细胞膜中的反射系数和渗透率

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摘要

The reflection coefficient (sigma) and permeability (P) of urea and ethylene glycol were determined by fitting the equations of Kedem and Katchalsky (1958) to the change in light scattering produced by adding a permeable solute to a red cell suspension. The measurements incorporated three important modifications: (a) the injection artifact was eliminated by using echinocyte cells; (b) the use of an additional adjustable parameter (Km), the effective dissociation constant at the inner side of the membrane; (c) the light scattering is not directly proportional to cell volume (as is usually assumed) because refractive index and scattering properties of the cell depend on the intracellular permeable solute concentration. This necessitates calibrating for known changes in refractive index (by the addition of dextran) and cell volume (by varying the NaCl concentration). The best fit was for sigma = 0.95, Po = 8.3 X 10(-4) cm/s, and Km = 100 mM for urea and sigma = 1.0, Po = 3.9 X 10(-4) cm/s, and Km = 30 mM for ethylene glycol. The effects of the inhibitors copper, phloretin, p- chloromercuriphenylsulfonate, and 5,5'-dithiobis (2-nitro) benzoic acid on the urea, ethylene glycol, and water permeability were determined. The results suggest that there are three separate, independent transport systems: one for water, one for urea and related compounds, and one for ethylene glycol and glycerol.
机译：尿素和乙二醇的反射系数（σ）和渗透率（P）通过将Kedem和Katchalsky（1958）的方程式与红细胞悬浮液中添加可渗透溶质所产生的光散射变化相拟合来确定。测量结果包含三个重要的修改：（a）通过使用棘突细胞消除注射伪影； （b）使用附加的可调参数（Km），即膜内侧的有效解离常数； （c）光散射与细胞体积不成正比（通常假定），因为细胞的折射率和散射特性取决于细胞内渗透性溶质浓度。这需要校准已知的折射率变化（通过添加右旋糖酐）和细胞体积（通过改变NaCl浓度）。最佳拟合是对于sigma = 0.95，Po = 8.3 X 10（-4）cm / s，对于尿素和sigma = 1.0，Po = 3.9 X 10（-4）cm / s，Km = 100 mM乙二醇为30 mM。确定了抑制剂铜，叶绿素，对-氯巯基苯基磺酸盐和5,5'-二硫代双（2-硝基）苯甲酸对尿素，乙二醇和水渗透性的影响。结果表明，存在三种独立的独立运输系统：一种用于水，一种用于尿素和相关化合物，以及一种用于乙二醇和甘油。

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