Fluid transport across cultured layers of corneal endothelium from aquaporin-1 null mice

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 μl 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 μl 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 μm sec −1: 74±4, n=19 vs. 44±4 μm sec −1, n=11, p