Reflection coefficients and water permeability in rat proximal tubule.
Reflection coefficients and water permeability in rat proximal tubule.
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大鼠近曲小管的反射系数和水渗透性。
DOI：
10.1152/ajprenal.1989.257.4.f658
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
Giebisch,G
中科院分区：
文献类型：
--
作者：
Green,R;Giebisch,G
采用肌动蛋白麻醉大鼠肾脏近端小管和小管周围毛细血管同时微灌注法测定反射系数。所有灌注液都含有氰化物以抑制主动运输；小管灌注液等渗，小管周围毛细血管灌注以NaCl、NaHCO3、l -葡萄糖或亚铁氰化钠配制的高渗溶液。对回收流体的测量可以计算出精确的平均梯度和离子通量；用菊粉测定净水通量。强加的梯度总是部分消散。假设l -葡萄糖为1，NaCl的反射系数为0.59 +/- 0.01，NaHCO3-的反射系数为0.87 +/- 0.04，亚铁氰化物的反射系数为0.96 +/- 0.07。近端小管透水性为1030 μ m /s。Cl-离子渗透率（21.6 +/- 1.3 X 10(-5) cm/s）大于Na+ (13.3 +/- 2.7 X 10(-5) cm/s)；l -葡萄糖的通透性为5.4 +/- 1.3 X 10(-5)，亚铁氰化物离子的通透性为2.7 +/- 0.9 X 10(-5) cm/s。由此可见，在大鼠近端小管中，NaCl和NaHCO3的反射系数均小于1.0，跨上皮的溶质不对称是液体重吸收的重要驱动力。此外，数据表明溶剂阻力对溶质运动有重要贡献。
Simultaneous microperfusion of proximal tubules and peritubular capillaries in kidneys of rats anesthetized with Inactin was used to measure reflection coefficients. All perfusates contained cyanide to inhibit active transport; the tubular perfusate was isotonic and the peritubular capillaries were perfused with solutions made hypertonic with NaCl, NaHCO3, L-glucose, or sodium ferrocyanide. Measurements of recollected fluid enabled a precise mean gradient and ionic fluxes to be calculated; net water flux was measured with inulin. Imposed gradients always partly dissipated. Reflection coefficients were 0.59 +/- 0.01 for NaCl, 0.87 +/- 0.04 for NaHCO3-, and 0.96 +/- 0.07 for ferrocyanide, assuming that L-glucose was 1. Water permeability of the proximal tubule was 1,030 microns/s. Ionic permeability of Cl- (21.6 +/- 1.3 X 10(-5) cm/s) was greater than that for Na+ (13.3 +/- 2.7 X 10(-5) cm/s); permeability for L-glucose was 5.4 +/- 1.3 X 10(-5), and for ferrocyanide ions 2.7 +/- 0.9 X 10(-5) cm/s. It is concluded that in rat proximal tubule both NaCl and NaHCO3 have reflection coefficients less than 1.0 and solute asymmetry across the epithelium is a significant driving force for fluid reabsorption. Furthermore the data suggest that there is a significant contribution of solvent drag to solute movement.