Graves C N, Sanders S S, Shoemaker R L, Rehm W S
Biochim Biophys Acta. 1975 May 21;389(3):550-6. doi: 10.1016/0005-2736(75)90165-0.
Corneas of bullfrog (Rana catesbeiana) were mounted between lucite chambers. A four-electrode system was used and the potential difference (PD) and the electrical resistance were measured. In intact corneas, the PD averaged 25 mV (acqueous side positive) and the electrical resistance 1.5 kQ - cm2. perfusion of the aqueous side with high K+ solutions resulted in a marked decrease in PD and a drop in the electrical resistance. Scraping the epithelium (leaving the stroma plus endothelium) resulted in a drop of the PD to about zero and a decrease in electrical resistance to about 0.1 kQ - CM2 and a very small PD response to a marked elevation of the K+ concentration on the aqueous side. On the basis of the above, it is obvious that the large delta PD in intact corneas, due to elevation of the K+ concentration, must be due to K+ diffusing from the aqueous side across the endothelium and stroma and reaching the epithelium. The duration of the PD response is therefore a measure of the resistance to diffusion of the stroma plus endothelium. A quantitiative analysis shows that under in vitro conditions the resistance of the endothelium plus stroma to the diffusion of ions is very low.
将牛蛙（牛蛙属）的角膜安装在有机玻璃小室之间。使用四电极系统测量电位差（PD）和电阻。在完整的角膜中，PD平均为25 mV（房水侧为正），电阻为1.5 kΩ - cm²。用高钾溶液灌注房水侧会导致PD显著降低和电阻下降。刮去上皮（保留基质和内皮）会导致PD降至约零，电阻降至约0.1 kΩ - cm²，并且当房水侧钾离子浓度显著升高时，PD反应非常小。基于以上情况，很明显，完整角膜中由于钾离子浓度升高而产生的大的PD变化，一定是由于钾离子从房水侧穿过内皮和基质并到达上皮。因此，PD反应的持续时间是基质加内皮对扩散阻力的一种度量。定量分析表明，在体外条件下，内皮加基质对离子扩散的阻力非常低。
