Maren T H, Wistrand P, Swenson E R, Talalay A B
Invest Ophthalmol. 1975 Sep;14(9):662-73.
Aqueous humor dynamics were studied in the dogfish, Squalus acanthias, using isotopically labeled inulin, Na+, Cl-, and HCO-3. Fluid production was 100 mul per hour, with a turnover rate constant of 0.4 hr.-1, about half that of mammals. The ciliary process contains carbonic anhydrase and Na-K-ATPase. Diffusion of Na+ and Cl- from plasma to aqueous was four to five times greater than flow, and from aqueous to vitreous, about 15 times greater. Sodium and chloride secretion is masked by the diffusion process; neither ouabain nor acetazolamide yield measurable effects on accumulation of these isotopes. HCO-3 accumulation in aqueous was very rapid and was reduced by inhibition of carbonic anhydrase. Analyses of the data suggest that newly formed aqueous has similar Na+ concentration to plasma, but is high in HCO-3 and low in Cl-. This anion pattern resembles mammalian aqueous humor, and cerebrospinal fluid and endolymph of other vertebrates. These and other data suggest that constant features of formation of these fluids in all phyla are sodium transport and formation of HCO-3 from CO2.
利用同位素标记的菊粉、Na⁺、Cl⁻和HCO₃⁻，对白斑角鲨（Squalus acanthias）的房水动力学进行了研究。房水生成速率为每小时100微升，周转率常数为0.4小时⁻¹，约为哺乳动物的一半。睫状体含有碳酸酐酶和钠钾ATP酶。从血浆到房水的Na⁺和Cl⁻扩散比流动大四到五倍，从房水到玻璃体的扩散约大15倍。钠和氯的分泌被扩散过程掩盖；哇巴因和乙酰唑胺对这些同位素的积累均未产生可测量的影响。房水中HCO₃⁻的积累非常迅速，并且通过抑制碳酸酐酶而减少。数据分析表明，新生成的房水的Na⁺浓度与血浆相似，但HCO₃⁻含量高而Cl⁻含量低。这种阴离子模式类似于哺乳动物的房水以及其他脊椎动物的脑脊液和内淋巴。这些以及其他数据表明，所有门类中这些液体形成的恒定特征是钠转运以及由CO₂形成HCO₃⁻。
