Levine S D, Kachadorian W A
J Membr Biol. 1981;61(2):135-9. doi: 10.1007/BF02007640.
Unstirred layers of water complicate the measurement of water permeability across epithelia. In the toad urinary bladder, the hormone vasopressin increases the osmotic water permeability of the granular epithelial cell's luminal membrane, and also leads to the appearance of aggregates of particles within this membrane. The aggregates appear to be markers for luminal membrane osmotic water permeability. This report analyzes the relationship between transbladder osmotic water flow and aggregate frequency, and demonstrates that flow across the bladder is significantly attenuated by unstirred layers of water or by structural barriers other than the luminal membrane when the luminal membrane is made permeable by vasopressin. This analysis in addition yields unique values for the permeabilities of both the luminal membrane and the barriers to water flow which lie in series with it.
静止的水层使跨上皮细胞水渗透性的测量变得复杂。在蟾蜍膀胱中，激素血管加压素可增加颗粒上皮细胞腔面膜的渗透水渗透性，并且还会导致该膜内出现颗粒聚集体。这些聚集体似乎是腔面膜渗透水渗透性的标志物。本报告分析了跨膀胱渗透水流与聚集体频率之间的关系，并证明当腔面膜因血管加压素而具有通透性时，跨膀胱的水流会因静止的水层或腔面膜以外的结构屏障而显著减弱。此外，该分析还得出了腔面膜以及与其串联的水流屏障的渗透率的独特值。
