Doughty M J
University of Waterloo, School of Optometry, Ontario, Canada.
Ophthalmic Physiol Opt. 1995 Nov;15(6):585-99.
Rabbit corneas were incubated, over 4 h in vitro, with the corneal epithelial surface exposed to various solutions to assess their utility as incubation solutions for physiological, pharmaceutical or toxicological studies. The corneal endothelium was perfused with a 35 mM bicarbonate-mixed salts solution equilibrated at 36 degrees C. Corneal thickness, corneal hydration or epithelial cell appearance (as assessed by scanning electron microscopy) were found to be similar to in vivo if a 35 mM bicarbonate, mixed salts solution (equilibrated with 5% CO2-air) was used for the epithelium. Some swelling (14 microns h-1), increased hydration and minor cell exfoliation were seen if this 35 mM bicarbonate solution was equilibrated with 5% CO2-95% O2 (hyperoxia). Solutions with only 5 mM bicarbonate (0.5% CO2-air) produced rapid swelling, large increases in hydration and marked cellular damage. Slightly hypertonic (310 mOsm kg-1) solutions containing 5 mM bicarbonate caused some swelling at 15 microns h-1, small increases in hydration and some cell damage but the swelling and cellular damage were further reduced by making the solution slightly more hypertonic (325 mOsm kg-1) by addition of NaCl and KCl. Saline (NaCl 0.9% or 0.97%) or phosphate-buffered saline (PBS) (300 mOsm kg-1) produced swelling at 21-28 microns h-1, 30% increases in hydration and almost total destruction of the superficial cell layers. These studies confirm in vivo experiments that saline (and also buffered saline solutions) are rather toxic to the corneal epithelium and thus should not be used as epithelial incubation solutions. Even when using mixed salts solutions and even with bicarbonate present, small differences in composition can have marked effects on corneal thickness, hydration or cell appearance. Hyperoxic solutions appear to be mildly cytotoxic compared with normoxic solutions.
将兔角膜在体外孵育4小时，使角膜上皮表面暴露于各种溶液中，以评估它们作为生理、药学或毒理学研究的孵育溶液的效用。用35 mM碳酸氢盐混合盐溶液在36℃下灌注角膜内皮。如果将35 mM碳酸氢盐混合盐溶液（用5% CO₂ -空气平衡）用于上皮，则发现角膜厚度、角膜水合作用或上皮细胞外观（通过扫描电子显微镜评估）与体内情况相似。如果该35 mM碳酸氢盐溶液用5% CO₂ - 95% O₂（高氧）平衡，则会出现一些肿胀（14微米/小时）、水合作用增加和轻微的细胞脱落。仅含5 mM碳酸氢盐（0.5% CO₂ -空气）的溶液会导致快速肿胀、水合作用大幅增加和明显的细胞损伤。含有5 mM碳酸氢盐的轻度高渗（310 mOsm/kg⁻¹）溶液在15微米/小时时会引起一些肿胀、水合作用小幅增加和一些细胞损伤，但通过添加NaCl和KCl使溶液略微更具高渗性（325 mOsm/kg⁻¹），肿胀和细胞损伤会进一步减少。生理盐水（0.9%或0.97% NaCl）或磷酸盐缓冲盐水（PBS）（300 mOsm/kg⁻¹）在21 - 28微米/小时时会产生肿胀、水合作用增加30%以及浅层细胞层几乎完全破坏。这些研究证实了体内实验的结果，即生理盐水（以及缓冲盐溶液）对角膜上皮相当有毒，因此不应用作上皮孵育溶液。即使使用混合盐溶液，即使存在碳酸氢盐，成分上的微小差异也会对角膜厚度、水合作用或细胞外观产生显著影响。与常氧溶液相比，高氧溶液似乎具有轻度细胞毒性。
