Study of fluid dynamics in the vitreous in normal and pathological eges

众所周知，玻璃体内的液体动力学取决于视网膜色素上皮(RPE)的功能。我们已经报道了使用Ussing小室的兔RPE脉络膜荧光素运动方式的特征，该系统适合于研究RPE的功能，即主动运输功能和阻止外源物质扩散的屏障功能。这一次，我们研究了羧基荧光素在分离的兔RPE脉络膜上的运动方式的特征。羧基荧光素被认为是研究细胞层屏障功能的一种更好的示踪剂，可以通过计算RPE对羧基荧光素的渗透系数来间接推测流体通过RPE的运动。羧基荧光素从脉络膜到玻璃体侧的运动是被动扩散的，而它从玻璃体到脉络膜侧的运动(向外运动)部分是通过主动传输的。在30微米的浓度下，兔RPE脉络膜对羧基荧光素的外向通透性约为内通透性的两倍。丙磺舒、哇巴因、2，4-二硝基苯酚和马尿酸盐显著降低对羧基荧光素的外向通透性。饱和动力学研究表明，羧基荧光素与载体的亲和力和最大反应速度低于荧光素。BSS+GSSG对羧基荧光素的通透性明显低于BSS或Krebs‘s Ringer液，提示GSSG对RPE的屏障功能具有良好的保护作用。

It is well known that fluid dynamics in the vitreous depends on the function of retinal pigment epithelium (RPE). We already reported characteristics of mode of fluorescein movement across the isolated rabbit RPE-choroid using Ussing's chamber and that this system is suited for studying the functions of RPE, i.e., active transporting function and barrier function against diffusion of exogenous substances. This time, we studied characteristics of mode of carboxyfluorescein movement across the isolated rabbit RPE-choroid. Carboxyfluorescein is known to be a much better tracer dye in studying the barrier function of cell layrs and it is expected that fluid movement across the RPE can be indirectly guessed by calculating the permeability coefficient of RPE to carboxyfluorescein.Movement of carboxyfluorescein across the isolated RPE-choroid from the choroid to the vitreous side (Inward movement) was found to be by passive diffusion, while its movement from the vitreous to the choroid side (Outward movement) was partly by active transport. At concentration of 30 muM, outward permeability of the isolated rabbit RPE-choroid to carboxyfluorescein was about twice of the inward permeability. Probenecid, ouabain, 2,4-dinitrophenol and hippurate significantly reduced the outward permeability to carboxyfluorescein. A saturation kinetic study revealed that affinity and maximum velocity of reaction of carboxyfluorescein to the carrier is lower than that of fluorescein. The inward permeability to carboxyfluorescein was significantly lower in BSS+GSSG than in BSS or Krebs' Ringer solution, which suggested that GSSG, oxidized glutathione, has beneficial effects on the barrier function of the RPE.The usage of carboxyfluorescein and Ussing's chamber is suggested to be a useful tool for studying active transport function which is associated with fluid movement across the RPE and barrier function of the RPE.