Kuang Kunyan, Yiming Maimaiti, Wen Quan, Li Yansui, Ma Li, Iserovich Pavel, Verkman A S, Fischbarg Jorge
Department of Ophthalmology, College of Physicians and Surgeons, Columbia University, 630 West 168th Street, New York, NY 10032, USA.
Exp Eye Res. 2004 Apr;78(4):791-8. doi: 10.1016/j.exer.2003.11.017.
We explored the role of AQP1, the only known aquaporin in corneal endothelium, on active fluid transport and passive osmotic water movements across corneal endothelial layers cultured from AQP1 null mice and wildtype mice. AQP1 null mice had grossly transparent corneas, just as wildtype mice. Endothelial cell layers grown on permeable supports transported fluid at rates of (in microl h(-1) cm(-2), n = 9 mean+/-s.e.): 4.3+/-0.6, wildtype mice (MCE); 3.5+/-0.6, AQP1 null mice (KMCE; difference not significant). The osmotic water flow (also in microl h(-1) cm(-2)) induced by a 100 mOsm sucrose gradient across MCE cell layers (8.7+/-0.6, n = 8) was significantly greater than that across KMCE (5.7+/-0.7, n = 6, p = 0.007). When plated on glass coverslips, plasma membrane osmotic water permeability determined by light scattering was significantly higher for cells from wildtype vs. AQP1 null mice (in microm sec(-1): 74+/-4, n = 19 vs. 44+/-4 microm sec(-1), n = 11, p < 0.001). Unexpectedly, after 10% hypo-osmotic challenge, the extent of the regulatory volume recovery was significantly reduced for AQP1 null mice cells (in%: MCE controls, 99+/-1, n = 19 vs. KMCE: 64+/-5, n = 11, p < 0.001). Thus, as in other 'low rate' fluid transporting epithelia, deletion of AQP1 in mice corneal endothelium reduces osmotic water permeability but not active transendothelial fluid transport. However, that deletion impaired the extent of regulatory volume decrease after a hypo-osmotic challenge, suggesting a novel role for AQP1 in corneal endothelium.
我们探究了水通道蛋白1（AQP1，角膜内皮中唯一已知的水通道蛋白）在源自水通道蛋白1基因敲除小鼠和野生型小鼠的角膜内皮细胞层上的主动液体转运及被动渗透水移动过程中的作用。水通道蛋白1基因敲除小鼠的角膜与野生型小鼠一样，大体上是透明的。在可渗透支持物上生长的内皮细胞层转运液体的速率为（微升·小时⁻¹·厘米⁻²，n = 9，平均值±标准误）：野生型小鼠（MCE）为4.3±0.6；水通道蛋白1基因敲除小鼠（KMCE）为3.5±0.6，差异不显著。由100毫渗蔗糖梯度诱导的跨MCE细胞层的渗透水流（同样为微升·小时⁻¹·厘米⁻²）（8.7±0.6，n = 8）显著大于跨KMCE的渗透水流（5.7±0.7，n = 6，p = 0.007）。当接种在玻璃盖玻片上时，通过光散射测定的野生型小鼠细胞相对于水通道蛋白1基因敲除小鼠细胞的质膜渗透水通透性显著更高（微秒⁻¹）：74±4，n = 19 对比 44±4微秒⁻¹，n = 11，p < 0.001）。出乎意料的是，在10%低渗刺激后，水通道蛋白1基因敲除小鼠细胞的调节性容积恢复程度显著降低（百分比）：MCE对照组为99±1，n = 19 对比 KMCE为64±5，n = 11，p < 0.001）。因此，与其他“低速率”液体转运上皮一样，小鼠角膜内皮中AQP1的缺失降低了渗透水通透性，但未影响主动跨内皮液体转运。然而，这种缺失损害了低渗刺激后的调节性容积减少程度，提示AQP1在角膜内皮中具有新的作用。
