Brahm J
J Gen Physiol. 1982 May;79(5):791-819. doi: 10.1085/jgp.79.5.791.
The diffusional water permeability of human red cells and ghosts was determined by measuring the rate of tracer efflux by means of an improved version of the continuous flow tube method, having a time resolution of 2-3 ms. At 25 degrees C, the permeability was 2.4 x 10(3) and 2.9 x 10(3) cm s-1 for red cells and ghosts, respectively. Permeability was affected by neither a change in pH from 5.5 to 9.5, nor by osmolality up to 3.3 osmol. Manganous ions at an extracellular concentration of 19 mM did not change diffusional water permeability, as recently suggested by NMR measurements. A "ground" permeability of 1 x 10(3) cm s-1 was obtained by inhibition with 1 mM of either p- chloromercuribenzoate (PCMB) or p-chloromercuribenzene sulfonate (PCMBS). Inhibition increased temperature dependence of water permeability for red cells and ghosts from 21 to 30 kJ mol-1 to 60 kJ mol-1. Although diffusional water permeability is about one order of magnitude lower than osmotic permeability, inhibition with PCMB and PCMBS, temperature dependence both before and after inhibition, and independence of osmolality showed that diffusional water permeability has qualitative features similar to those reported for osmotic permeability, which indicates that the same properties of the membrane determine both types of transport. It is suggested that the PCMB(S)-sensitive permeability above the ground permeability takes place through the intermediate phase between integral membrane proteins and their surrounding lipids.
采用连续流管法的改进版本，通过测量示踪剂流出速率来测定人红细胞和血影的扩散水渗透性，该方法的时间分辨率为2 - 3毫秒。在25℃时，红细胞和血影的渗透性分别为2.4×10³和2.9×10³厘米/秒。pH值从5.5变化到9.5，以及渗透压高达3.3渗透压时，渗透性均不受影响。细胞外浓度为19毫摩尔的锰离子并未改变扩散水渗透性，正如最近核磁共振测量所表明的那样。用1毫摩尔对氯汞苯甲酸（PCMB）或对氯汞苯磺酸盐（PCMBS）抑制可得到“基础”渗透性为1×10³厘米/秒。抑制作用使红细胞和血影的水渗透性温度依赖性从21千焦/摩尔增加到30千焦/摩尔变为60千焦/摩尔。尽管扩散水渗透性比渗透渗透性低约一个数量级，但PCMB和PCMBS的抑制作用、抑制前后的温度依赖性以及渗透压独立性表明，扩散水渗透性具有与报道的渗透渗透性相似的定性特征，这表明膜的相同特性决定了这两种运输类型。有人提出，高于基础渗透性的对PCMB（S）敏感的渗透性是通过整合膜蛋白与其周围脂质之间的中间相发生的。
