Fischbarg J, Hofer G l, Koatz R A
Biochim Biophys Acta. 1980 Dec 2;603(1):198-206. doi: 10.1016/0005-2736(80)90402-2.
The present study shows that the inclusion of 5% Dextran (average mol. wt. 40 000) in solutions to preserve in vitro rabbit corneal endothelium induces a sizable osmotic flow across the preparation which is superimposed on the existing fluid transport. Furthermore, even after fluid transport ceases due to in vitro deterioration, the Dextran-induced flow remains for some addition time. The osmotic permeability was 162 +/- 17 micrometer/s in the presence of glucose and 451 +/- 84 micrometer/s in its absence. The latter, comparatively high value suggests that such osmotic flow traverses the intracellular junctions. In addition, temporary (10--15 min) imposition of an osmotic gradient has a separate stimulatory 'priming' effect on the rate of fluid transport. Thus, the rate of fluid pumping increased by about 40% after challenge with Dextran. It was further noted that, after addition of Dextran, preparations in the absence of glucose escape gross deterioration for a time longer than those in the presence of glucose. On the other hand, mere addition of Dextran to a glucose-containing solution does not appear to prolong the estimated 'survival time' of the pumping mechanism. The sizable osmotic flows and the priming effect described here may provide a physiological context with which previously described Dextran effects on cornea preservation can now be compared.
本研究表明，在用于体外保存兔角膜内皮的溶液中加入5%的葡聚糖（平均分子量40000）会诱导相当大的渗透流穿过该制剂，此渗透流叠加在现有的液体转运之上。此外，即使由于体外退变导致液体转运停止后，葡聚糖诱导的流动仍会持续一段时间。在有葡萄糖存在的情况下，渗透渗透率为162±17微米/秒，在无葡萄糖时为451±84微米/秒。后一个相对较高的值表明这种渗透流穿过细胞间连接。此外，暂时（10 - 15分钟）施加渗透梯度对液体转运速率有单独的刺激“引发”作用。因此，用葡聚糖刺激后，液体泵浦速率增加了约40%。还进一步注意到，加入葡聚糖后，无葡萄糖的制剂比有葡萄糖的制剂在一段时间内避免了严重退变。另一方面，仅向含葡萄糖的溶液中加入葡聚糖似乎并不会延长泵浦机制的估计“存活时间”。这里描述的相当大的渗透流和引发作用可能提供了一个生理学背景，据此现在可以比较先前描述的葡聚糖对角膜保存的影响。
