Laboratories of The Rockefeller Institute for Medical Research.
J Gen Physiol. 1940 Jan 20;23(3):365-90. doi: 10.1085/jgp.23.3.365.
In various models designed to imitate living cells the surface of the protoplasm is represented by guaiacol which acts in some respects like certain protoplasmic surfaces. The behavior of water in these models presents interesting features and if these occur in vivo, as appears possible, they may help to explain some of the puzzling aspects of water relations in the living organism. When sufficient trichloroacetic acid is added to a two-phase system of water and guaiacol the two phases fuse into one. The effect of the acid is due to its attraction for water and for guaiacol. This is shown by the following facts. During the addition of the acid the mole fraction of water in the guaiacol phase increases but the activity of water in the guaiacol phase falls off. The activity coefficient of water may fall to less than one twelfth the value it had before acid was added. The behavior of guaiacol presents a similar picture. During the addition of acid the mole fraction of guaiacol in the aqueous phase increases but the activity of the guaiacol in the aqueous phase presumably decreases. Its activity coefficient calculated on this basis may fall to about one ninth of the value it had before the acid was added. Somewhat similar results are obtained when acetone is substituted for trichloroacetic acid or when ethanol is substituted for trichloroacetic acid and ethylene chloride for guaiacol. As trichloroacetic acid increases the mutual solubility of guaiacol and water we find that guaiacol saturated with water and having a high vapor pressure of water can take up water from an aqueous solution of trichloroacetic acid with a low vapor pressure of water: acid passes from the aqueous to the guaiacol phase, thus raising the vapor pressure of water in the aqueous phase and lowering it in the guaiacol phase. Diffusion experiments present some interesting features. When an aqueous solution, A, of trichloroacetic acid is separated by a layer of guaiacol, B, from distilled water, C, under certain conditions water moves from A to C. This depends on the fact that acid moves in the same direction and appears to carry water with it. Similar but less striking results were obtained with acetone diffusing through guaiacol and with ethanol diffusing through ethylene chloride. These phenomena differ from "anomalous osmosis" through solid membranes if it depends, as many suppose, on the diffusion of electrolytes through pores. We therefore suggest the term "anaphoresis" for the phenomena described here. Measurements of the mutual solubilities of water, guaiacol, and trichloroacetic acid and of water, guaiacol, and acetone are given and are discussed in relation to the diffusion experiments. To give a complete picture of the process of diffusion we need to know the activities and concentrations in all parts of the system. The difficulties of achieving this are obvious. The solubility relations are such that a concentration gradient of trichloroacetic acid in guaiacol produces a concentration gradient of water in the same direction, but the activity gradient of water is in the opposite direction. Since in certain respects guaiacol acts like some protoplasmic surfaces it seems possible that similar phenomena may occur in living cells. If so these results have an obvious bearing on the movement of water in the organism and on methods of studying permeability. It becomes necessary to know to what extent a substance entering or leaving the cell appears to carry water with it in the manner here indicated. In certain of the diffusion experiments the water takes a circular path, passing out of the dilute solution at one point and back into it (as vapor) at another. This circular path recalls the situation in the kidney where the water continually passes out of the blood into the glomerulus and tubule and then back into the blood from the tubule (where the solution is more concentrated). In both cases the circular path of the water is an essential feature.
在各种模拟活细胞的模型中，质膜由愈创木酚表示，它在某些方面的行为类似于某些质膜表面。这些模型中水分子的行为呈现出有趣的特征，如果这些特征在体内发生（似乎是可能的），它们可能有助于解释活生物体中水分关系的一些令人困惑的方面。当向水和愈创木酚的两相系统中加入足够的三氯乙酸时，两相融合为一。酸的作用归因于它对水和愈创木酚的吸引力。以下事实表明了这一点。在添加酸的过程中，愈创木酚相中的水的摩尔分数增加，但愈创木酚相中的水的活度下降。水的活度系数可能降至添加酸之前的十二分之一以下。愈创木酚的行为呈现出类似的图景。在添加酸的过程中，愈创木酚相中的愈创木酚摩尔分数增加，但愈创木酚在水相中的活度可能降低。根据这个基础计算的愈创木酚的活度系数可能降至添加酸之前的约九分之一。当用丙酮代替三氯乙酸或用乙醇代替三氯乙酸和氯乙烯代替愈创木酚时，会得到一些类似的结果。随着三氯乙酸的增加，愈创木酚和水的互溶性增加，我们发现愈创木酚饱和水且水的蒸气压高，可以从水蒸气压低的三氯乙酸水溶液中吸收水：酸从水相向愈创木酚相移动，从而提高了水在水相中的蒸气压，并降低了它在愈创木酚相中的蒸气压。扩散实验呈现出一些有趣的特征。当三氯乙酸的水溶液 A 通过一层愈创木酚 B 与蒸馏水 C 隔开时，在某些条件下，水从 A 向 C 移动。这取决于酸朝同一方向移动并似乎将水一起带走的事实。用丙酮通过愈创木酚和乙醇通过氯乙烯扩散时，得到了类似但不那么显著的结果。这些现象与通过固体膜的“异常渗透”不同，如果它像许多人假设的那样取决于电解质通过孔隙的扩散，那么我们建议使用“反电泳”这个术语来描述这里描述的现象。给出了水、愈创木酚和三氯乙酸以及水、愈创木酚和丙酮的互溶解度的测量值，并根据扩散实验进行了讨论。为了完整描述扩散过程，我们需要知道系统各部分的活度和浓度。实现这一目标的困难是显而易见的。溶解度关系使得三氯乙酸在愈创木酚中的浓度梯度产生相同方向的水浓度梯度，但水的活度梯度则相反。由于愈创木酚在某些方面的行为类似于某些质膜表面，因此似乎可能在活细胞中发生类似的现象。如果是这样，这些结果对生物体中水分的运动以及渗透性研究方法有明显的影响。我们有必要知道，进入或离开细胞的物质在多大程度上以这里所示的方式携带水。在某些扩散实验中，水会形成一个循环路径，从一个点离开稀溶液并以蒸汽的形式返回另一个点。这种循环路径让人联想到肾脏中的情况，在肾脏中，水不断从血液进入肾小球和肾小管，然后从肾小管（那里的溶液浓度更高）回到血液中。在这两种情况下，水的循环路径都是一个重要特征。
