Finkelstein A
J Gen Physiol. 1976 Aug;68(2):137-43. doi: 10.1085/jgp.68.2.137.
In artificial lipid bilayer membranes, the ratio of the water permeability coefficient (Pd(water)) to the permeability coefficient of an arbitrary nonelectrolyte such as n-butyramide (Pd(n-butyramide)) remains relatively constant with changes in lipid composition and temperature, even though the individual Pd's increase more than 100-fold. I propose that this is a general rule that also holds for the lipid bilayers of cells and tissues, and that therefore if Pd(water)/Pd(solute greatly exceeds the value found for artifical lipid bilayers (where "solute" is a molecule, such as 1,6 hexanediol or n-butyramide, that crosses the cell membrane by a solubility-diffusion mechanism without the aid of a special transporting system), then water crosses the cell membrane via aqueous pores. Applying this criterion to the toad urinary bladder, we find that even in the unstimulated bladder, water probably crosses the luminal membrane primarily through small aqueous pores, and that this almost certainly the case after antidiuretic hormone (ADH) stimulation. I suggest that ADH stimulation ultimately leads either to formation (or enlargement) of pores, by the rearrangement of preexisting subunits, or to an unplugging of these pores.
在人工脂质双分子层膜中，水渗透系数（Pd(水)）与任意非电解质（如正丁酰胺）的渗透系数（Pd(正丁酰胺)）之比，在脂质组成和温度变化时保持相对恒定，尽管各个Pd值增加超过100倍。我提出这是一条普遍规律，也适用于细胞和组织的脂质双分子层，因此，如果Pd(水)/Pd(溶质)大大超过人工脂质双分子层的值（其中“溶质”是一种分子，如1,6 -己二醇或正丁酰胺，通过溶解扩散机制穿过细胞膜而无需特殊转运系统的帮助），那么水通过水通道穿过细胞膜。将此标准应用于蟾蜍膀胱，我们发现即使在未受刺激的膀胱中，水可能主要通过小水通道穿过腔面膜，而在抗利尿激素（ADH）刺激后几乎肯定是这种情况。我认为ADH刺激最终要么导致通过预先存在的亚基重排形成（或扩大）通道，要么导致这些通道的堵塞解除。
