SCHULTZ S G, ZALUSKY R
J Gen Physiol. 1964 Jan;47(3):567-84. doi: 10.1085/jgp.47.3.567.
The transmural potential difference, short-circuit current, and Na fluxes have been investigated in an in vitro preparation of isolated rabbit ileum. When the tissue is perfused with a physiological buffer, the serosal surface is electrically positive with respect to the mucosal surface and the initial potential difference in the presence of glucose averages 9 mv. Unidirectional and net Na fluxes have been determined under a variety of conditions, and in each instance, most if not all of the simultaneously measured short-circuit current could be attributed to the active transport of Na from mucosa to serosa. Active Na transport is dependent upon the presence of intact aerobic metabolic pathways and is inhibited by low concentrations of ouabain in the serosal medium. A method is described for determining whether a unidirectional ionic flux is the result of passive diffusion alone, in the presence of active transport of that ion in the opposite direction. Using this method we have demonstrated that the serosa-to-mucosa flux of Na may be attributed to passive diffusion with no evidence for the presence of carrier-mediated exchange diffusion or the influence of solvent-drag.
在离体兔回肠的体外制备物中，对跨壁电位差、短路电流和钠通量进行了研究。当用生理缓冲液灌注组织时，浆膜表面相对于粘膜表面呈电正性，在有葡萄糖存在的情况下，初始电位差平均为9毫伏。已经在各种条件下测定了单向和净钠通量，并且在每种情况下，同时测量的短路电流中的大部分（如果不是全部）可归因于钠从粘膜到浆膜的主动转运。主动钠转运依赖于完整的有氧代谢途径的存在，并受到浆膜介质中低浓度哇巴因的抑制。描述了一种在存在该离子相反方向的主动转运的情况下，确定单向离子通量是否仅为被动扩散结果的方法。使用这种方法，我们已经证明钠从浆膜到粘膜的通量可能归因于被动扩散，没有证据表明存在载体介导的交换扩散或溶剂拖曳的影响。
