Amis E J, Wendt D J, Erickson E D, Yu H
Biochim Biophys Acta. 1981 Jun 22;644(2):201-10. doi: 10.1016/0005-2736(81)90376-x.
The permeability of the bleached disk membrane of retinal rod outer segments to univalent and divalent ions is studied by light scattering. The membranes are isolated from frozen dark-adapted bovine retinae, swollen into spherical vesicles in a hypotonic medium and bleached in dilute suspension and their size is determined by elastic and quasi-elastic light scatterings. Various electrolytes are then added to the suspending medium in order to examine their osmotic activity relative to the vesicles deformation characteristics. By following the deformation behavior of the membrane vesicles by elastic light scattering in terms of the oblate ellipsoidal shell model, the osmotic activity of a given electrolyte is qualitatively deduced and thereby the permeability of the membrane to the electrolyte is ranked in reference to a chosen standard, i.e., sucrose. By this method, we show that the permeabilities to Na+, K+, Mg2+ and Ca2+ are all alike, and those to halides (F-, Cl-, Br-, I-), nitrate and phosphates (HPO4(2-)/H2PO4-) are similar. Acetate, however, is about 3-times more permeative, while sulfate is less permeative than the other anions by about the same factor. The viability of our method is checked with use of an ionophore, lasolocid (X-537A), by establishing partial recovery from the osmotic deformation through the suppression of the cation osmotic effect. Ion-induced aggregation and pH-dependent size and shape changes are both found to be insignificant.
通过光散射研究视网膜视杆外段漂白盘膜对单价和二价离子的通透性。膜从冷冻的暗适应牛视网膜中分离出来，在低渗介质中膨胀成球形囊泡，并在稀悬浮液中漂白，其大小通过弹性和准弹性光散射来确定。然后向悬浮介质中添加各种电解质，以检查它们相对于囊泡变形特性的渗透活性。通过根据扁椭球壳模型利用弹性光散射跟踪膜囊泡的变形行为，定性推断给定电解质的渗透活性，从而参照选定标准（即蔗糖）对膜对电解质的通透性进行排序。通过这种方法，我们表明对Na +、K +、Mg2 +和Ca2 +的通透性都相似，对卤化物（F -、Cl -、Br -、I -）、硝酸盐和磷酸盐（HPO4(2 -)/H2PO4 -）的通透性相似。然而，乙酸盐的通透性约为其他离子的3倍，而硫酸盐的通透性比其他阴离子低约相同倍数。通过使用离子载体拉沙洛西（X - 537A），通过抑制阳离子渗透效应使渗透变形部分恢复，来检验我们方法的可行性。发现离子诱导的聚集以及pH依赖性的大小和形状变化都不显著。
