Toris C B, Pederson J E, Tsuboi S, Gregerson D S, Rice T J
Department of Ophthalmology, University of Minnesota, Minneapolis 55455.
Invest Ophthalmol Vis Sci. 1990 Jan;31(1):43-53.
The hypothesis that uveal vessels absorb fluid was tested by measuring the albumin in extravascular uveal tissues and in plasma. From these results the effective albumin concentration was calculated in both rabbits and monkeys. Three separate methods were used to measure uveal albumin, and the results of these were compared. In method 1, the intravenous fluorescein isothiocyanate (FITC)-albumin concentration found in the uvea 5 min after injection (intravascular tracer) was subtracted from that found 2 hr after injection (intravascular plus extravascular tracer) to determine the extravascular albumin concentration. In method 2, intravenous FITC-albumin was followed by vascular washout after a 2-hr equilibration period to determine extravascular uveal albumin. In method 3, the endogenous extravascular albumin concentration of uveal tissues was measured with an enzyme-linked immunosorbent assay (ELISA) after vascular washout. The effective albumin concentration was determined by dividing the data in methods 1, 2, and 3 by the extravascular albumin space volume. The effective albumin concentration in monkey (as percentage of plasma) was, for methods 1, 2, and 3: iris 2, 3, and 4%; pars plicata 14, 12, and 7%; pars plana 2, 10, and 12%; and choroid 2, 12, and 10%, respectively. In rabbit, the extravascular albumin concentrations were: iris 10, 21, and 7%; pars plicata 69, 26, and 39%; pars plana 41, 46, and 10%; and choroid 88, 30, and 26%, respectively. These findings are lower than previously reported in rabbits, yet are consistent with previous estimates in monkeys. These results support the hypothesis that uveal vessels are capable of fluid absorption, since a large colloid osmotic gradient exists across the vessel wall.
通过测量血管外葡萄膜组织和血浆中的白蛋白，对葡萄膜血管吸收液体的假说进行了验证。根据这些结果，计算了兔子和猴子体内的有效白蛋白浓度。采用三种不同方法测量葡萄膜白蛋白，并对结果进行比较。方法1：用注射后5分钟（血管内示踪剂）葡萄膜中静脉注射异硫氰酸荧光素（FITC）-白蛋白浓度减去注射后2小时（血管内加血管外示踪剂）的浓度，以确定血管外白蛋白浓度。方法2：静脉注射FITC-白蛋白，平衡2小时后进行血管冲洗，以确定血管外葡萄膜白蛋白。方法3：血管冲洗后，用酶联免疫吸附测定（ELISA）测量葡萄膜组织的内源性血管外白蛋白浓度。有效白蛋白浓度通过将方法1、2和3中的数据除以血管外白蛋白空间体积来确定。猴子中，方法1、2和3的有效白蛋白浓度（占血浆的百分比）分别为：虹膜2%、3%和4%；睫状突14%、12%和7%；睫状体平坦部2%、10%和12%；脉络膜2%、12%和10%。在兔子中，血管外白蛋白浓度分别为：虹膜10%、21%和7%；睫状突69%、26%和39%；睫状体平坦部41%、46%和10%；脉络膜88%、30%和26%。这些发现低于之前在兔子中的报道，但与之前对猴子的估计一致。这些结果支持了葡萄膜血管能够吸收液体的假说，因为血管壁两侧存在很大的胶体渗透压梯度。
