Pitterich H, Lawaczeck R
Biochim Biophys Acta. 1985 Dec 5;821(2):233-42. doi: 10.1016/0005-2736(85)90092-6.
The diffusional permeability of water across membranes from bovine and human erythrocyte ghosts was measured by a recently developed method which is based on the different indices of refraction of H2O and 2H2O. Resealed erythrocyte ghosts were prepared by a gel-filtration technique. Pd (2H2O/H2O) values of 1.2 X 10(-3) cm/s (human) and 1.7 X 10(-3) cm/s (bovine) were calculated at 20 degrees C. The activation energies of the water exchange were 23.5 kJ/mol (human) and 25.4 kJ/mol (bovine). Treatment of the ghosts with p-chloromercuribenzenesulfonic acid (PCMBS) led to a 60-70% inhibition of the diffusional water exchange. The pH equilibration across membranes of erythrocyte ghosts was measured by intracellular carboxyfluorescein. The rates of proton flux after pH-jumps (pH 7.3 to pH 6.1) were about 100-fold lower than those of the water exchange and dependent on the kind of anions present (Cl-, NO-3, SO2-4). The activation energies of proton flux were 60-70 kJ/mol. 4,4'-Diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS) inhibited the exchange by 97-98% and lowered the activation energy. The inhibitor of water exchange, PCMBS, increased the proton-permeation rate by a factor of 4-5. It is assumed that the rate-limiting step for the proton permeation is determined by the anion exchange. Under this condition our results are not in accord with one channel as a common pathway for both the passive water and anion transport.
采用一种最近开发的基于H₂O和²H₂O不同折射率的方法，测量了水透过牛和人红细胞血影膜的扩散渗透率。通过凝胶过滤技术制备重新封闭的红细胞血影。在20℃下计算得到的Pd(²H₂O/H₂O)值，人红细胞为1.2×10⁻³cm/s，牛红细胞为1.7×10⁻³cm/s。水交换的活化能，人红细胞为23.5kJ/mol，牛红细胞为25.4kJ/mol。用对氯汞苯磺酸（PCMBS）处理血影导致扩散水交换受到60 - 70%的抑制。通过细胞内羧基荧光素测量红细胞血影膜两侧的pH平衡。pH跃变（从pH 7.3到pH 6.1）后质子通量速率比水交换速率低约100倍，且取决于存在的阴离子种类（Cl⁻、NO₃⁻、SO₄²⁻）。质子通量的活化能为60 - 70kJ/mol。4,4'-二异硫氰基芪-2,2'-二磺酸（DIDS）抑制交换97 - 98%并降低活化能。水交换抑制剂PCMBS使质子渗透速率提高4 - 5倍。假定质子渗透的限速步骤由阴离子交换决定。在这种情况下，我们的结果与被动水和阴离子运输共用一个通道的观点不一致。
