Department of Physiology, University of California Medical Center, 90024, Los Angeles, California.
J Membr Biol. 1971 Dec;5(4):297-318. doi: 10.1007/BF01957348.
The permeability of the rabbit gallbladder epithelium to nonelectrolytes was determinted by radioactive tracer techniques and by a rapid osmotic procedure. As expected from empirical and theoretical considerations, there was a good agreement between the selectivity sequences obtained by the two methods for the sixteen compounds used in this study. Although the permeability coefficients are directly related to their bulk-phase partition coefficients, the gallbladder behaves as if the membranes controlling selectivatity are more hydrophilic than isobutanol. The relation between permeability coefficients and molecular weight also show that these membranes are less viscous than other single cell membranes. Small polar solutes exhibit lower apparent activiation energies for permeation than larger solutes, and this is taken as support for the view that small polar molecules permeate across this tissue via a polar pathway. Inutin and sucrose permeability coefficients are in the ratio of their free-solution diffusion coefficients, and the apparent surcose activation energy is indistinguishable from that reported for diffusion in aqueous solution. These latter observations may be explained by the presence of a few large "pores" in the epithelium.
用放射性示踪技术和快速渗透法测定了兔胆囊上皮对非电解质的通透性。正如经验和理论考虑所预期的那样，这两种方法对本研究中使用的 16 种化合物得出的选择性顺序非常吻合。尽管渗透系数与它们在总体相中的分配系数直接相关，但胆囊的行为就好像控制选择性的膜比异丁醇更亲水。渗透系数与分子量之间的关系也表明，这些膜比其他单细胞膜的粘性小。小的极性溶质的渗透表观活化能比大溶质的渗透表观活化能低，这支持了这样一种观点，即小的极性分子通过极性途径穿过这种组织渗透。肌醇和蔗糖的渗透系数与它们在游离溶液中的扩散系数之比，并且蔗糖的表观活化能与在水溶液中扩散的报道值无法区分。这些后一种观察结果可以用上皮中存在少量大“孔”来解释。
