Lim J J, Ussing H H
J Membr Biol. 1982;65(3):197-204. doi: 10.1007/BF01869963.
Instead of the conventional steady-state fluxes, the presteady-state fluxes of 22Na across the rabbit corneal endothelium were measured. In contrast to reports that there is no net Na+ movement across the corneal endothelium, we find a net transport of Na+ across this tissue. The direction of net Na+ flux is from the stromal to the aqueous side and the magnitude is 2.3 +/- 0.4 mueq/cm2 X hr (n = 11, SEM). Net Na+ transport is inhibited in the presence of ouabain (10(-4) M). Acetazolamide (10(-4) M) has only a slight inhibitory effect on the rate of Na+ transport but decreases the transendothelial potential difference by about 30%. The passive component of the Na+ transport has been estimated by analyzing the presteady-state influx and efflux curves and found to occur 10% via cellular and 90% via paracellular routes. The analysis for the separation of the pathways has been based on a recently proposed theory which holds that the flux ratio, regardless of its driving forces, is independent of time.
我们测量了22Na跨兔角膜内皮的前稳态通量，而不是传统的稳态通量。与报道称没有Na+跨角膜内皮的净移动相反，我们发现有Na+跨该组织的净转运。净Na+通量的方向是从基质侧到房水侧，大小为2.3±0.4微当量/平方厘米×小时（n = 11，标准误）。在哇巴因（10(-4) M）存在的情况下，净Na+转运受到抑制。乙酰唑胺（10(-4) M）对Na+转运速率只有轻微的抑制作用，但使跨内皮电位差降低约30%。通过分析前稳态流入和流出曲线估计了Na+转运的被动成分，发现10%通过细胞途径，90%通过细胞旁途径发生。对途径分离的分析基于最近提出的一种理论，该理论认为通量比，无论其驱动力如何，都与时间无关。
