Gutknecht J, Tosteson D C
Science. 1973 Dec 21;182(4118):1258-61. doi: 10.1126/science.182.4118.1258.
Chemical reactions in the aqueous unstirred layers of solution adjacent to a membrane can have dramatic effects on the diffusion of solutes across that membrane. This is demonstrated by the diffusion of labeled salicylate and salicylic acid across a phospholipid bilayer membrane. Two types of chemical reactions are considered. The first is an isotopic exchange reaction between the ionic and nonionic forms of a weak acid, HA + A(-) [unknown] HA + A(-). This reaction provides a way of estimating the true membrane permeability to a highly permeant weak acid and also a way of estimating the thickness of the unstirred layers. The second chemical reaction, the dissociation of a weak acid, HA [unknown] H(+) + A(-), can be used to show how the presence or absence of buffers in the unstirred layers controls the net transport of permeant weak acids across a membrane. In principle, the addition of appropriate "antacid" buffers to salicylates can increase their rate of absorption from the stomach.
与膜相邻的溶液中未搅拌水层中的化学反应，会对溶质跨膜扩散产生显著影响。这一点通过标记的水杨酸盐和水杨酸跨磷脂双分子层膜的扩散得到了证明。考虑了两种化学反应。第一种是弱酸离子形式和非离子形式之间的同位素交换反应，HA + A(-) [未知] HA + A(-)。该反应提供了一种估算高渗透性弱酸真实膜渗透率的方法，也提供了一种估算未搅拌层厚度的方法。第二种化学反应，弱酸的解离，HA [未知] H(+) + A(-)，可用于表明未搅拌层中缓冲剂的存在与否如何控制渗透性弱酸跨膜的净转运。原则上，向水杨酸盐中添加合适的“抗酸”缓冲剂可提高其从胃中的吸收速率。
