Takeuchi A, Kricorian G, Marmor M F
Department of Ophthalmology, Stanford University School of Medicine, California, USA.
Invest Ophthalmol Vis Sci. 1995 Jun;36(7):1298-305.
The subretinal fluid of serous retinal detachments contains protein, but little is known about its origin and fate. The authors designed experiments to study the rate and route of albumin movement out of the subretinal space.
Experimental retinal detachments were made in Dutch rabbits by injecting Hanks' balanced salt solution containing serum levels (approximately 30 mg/ml) of fluorescein isothiocyanate (FITC) albumin into the subretinal space through a micropipette. Subretinal, vitreous, and serum fluid samples were withdrawn 0 to 4 hours later through a similar micropipette and were analyzed for osmolality, FITC albumin content (by fluorophotometry) and FITC+native albumin content (by gel electrophoresis). Sodium iodate was injected intravenously in some rabbits to damage the retinal pigment epithelium (RPE).
Albumin injected into the subretinal fluid diffused steadily into the vitreous, and its concentration decreased by approximately 5% per hour. This rate was unaffected by RPE damage. Albumin did not move into the bloodstream unless the RPE was damaged with sodium iodate, and then it crossed the RPE at approximately 25% of the rate at which it moved into the vitreous. Subretinal fluid osmolality remained within the range of 293 to 294 mOsm/kg despite protein movement and the continual absorption of fluid from the detachments.
These results show that albumin in the subretinal space diffuses readily into the vitreous, and subretinal osmolality changes are rapidly equilibrated with the vitreous. Albumin does not cross normal RPE, and it crosses iodate-damaged RPE more slowly than it crosses retina. Thus, there must be a constant supply of albumin if high subretinal concentrations are to be sustained in clinical serous detachments.
浆液性视网膜脱离的视网膜下液含有蛋白质，但其来源和去向却知之甚少。作者设计了实验来研究白蛋白从视网膜下间隙移出的速率和途径。
通过微量移液器将含有血清水平（约30mg/ml）异硫氰酸荧光素（FITC）白蛋白的汉克斯平衡盐溶液注入荷兰兔的视网膜下间隙，造成实验性视网膜脱离。0至4小时后，通过类似的微量移液器抽取视网膜下、玻璃体和血清样本，分析其渗透压、FITC白蛋白含量（通过荧光光度法）和FITC + 天然白蛋白含量（通过凝胶电泳）。对一些兔子静脉注射碘酸钠以损伤视网膜色素上皮（RPE）。
注入视网膜下液的白蛋白稳定地扩散到玻璃体中，其浓度每小时下降约5%。该速率不受RPE损伤的影响。除非用碘酸钠损伤RPE，白蛋白不会进入血液循环，此时它穿过RPE的速率约为进入玻璃体速率的25%。尽管有蛋白质移动以及视网膜下液持续吸收，但视网膜下液渗透压仍保持在293至294mOsm/kg范围内。
这些结果表明，视网膜下间隙中的白蛋白很容易扩散到玻璃体中，视网膜下渗透压变化迅速与玻璃体达到平衡。白蛋白不会穿过正常的RPE，它穿过碘酸盐损伤的RPE比穿过视网膜更慢。因此，如果要在临床浆液性脱离中维持高视网膜下浓度，必须有白蛋白的持续供应。
