Sansom S C, Senekjian H O, Knight T F, Frommer P, Weinman E J
Proc Soc Exp Biol Med. 1983 Jan;172(1):111-7. doi: 10.3181/00379727-172-41536.
Simultaneous in vivo capillary and luminal microperfusion studies were performed in the superficial proximal convoluted tubule of the rat to determine the effect of intraluminal bicarbonate, the imposition of a transepithelial chloride gradient, and the addition of organic solutes to the luminal perfusion solution on the rates of water absorption (Jv). The capillary perfusion solution contained NaCl, NaHCO3, and KCl. Perfusion of both capillary and lumen with the same solution resulted in a Jv of 3.01 +/- 0.24 nl/min/mm. Imposition of a transepithelial chloride gradient (equimolar substitution of NaCl for NaHCO3 in the luminal solution) resulted in a Jv of 3.18 +/- 0.21 nl/min/mm (P = NS). Addition of cyanide to both solutions in the presence of a chloride gradient resulted in a significantly lower Jv of 2.21 +/- 0.19 nl/min/mm. Luminal substitution of Na cyclamate for NaHCO3 resulted in a solution containing no bicarbonate and no chloride gradient. Jv averaged 0.34 +/- 0.08 nl/min/mm. Addition of cyanide to the solution totally inhibited Jv. The addition of D-glucose, L-alanine, or both, to luminal solutions containing bicarbonate or in the presence of a chloride gradient did not significantly affect Jv. Addition of both organic solutes to the NaCl-Na cyclamate luminal solution resulted in a significantly higher Jv of 0.77 +/- 0.14 nl/min/mm. These studies indicate that Jv in the rat superficial proximal tubule is influenced by active sodium transport, by the presence of bicarbonate in the lumen, and/or by the imposition of a transepithelial chloride gradient. The organic solutes D-glucose and L-alanine also influence water absorption, but this effect could only be demonstrated under some experimental conditions.
在大鼠浅表近端曲管中进行了同步体内毛细血管和管腔微灌注研究，以确定管腔内碳酸氢盐、跨上皮氯梯度的施加以及向管腔灌注溶液中添加有机溶质对水吸收速率（Jv）的影响。毛细血管灌注溶液含有氯化钠、碳酸氢钠和氯化钾。用相同溶液灌注毛细血管和管腔时，Jv为3.01±0.24 nl/分钟/毫米。施加跨上皮氯梯度（在管腔溶液中用等摩尔的氯化钠替代碳酸氢钠）导致Jv为3.18±0.21 nl/分钟/毫米（P=无显著差异）。在存在氯梯度的情况下，向两种溶液中添加氰化物导致Jv显著降低，为2.21±0.19 nl/分钟/毫米。用甜蜜素钠替代管腔中的碳酸氢钠，得到一种不含碳酸氢盐且无氯梯度的溶液。Jv平均为0.34±0.08 nl/分钟/毫米。向溶液中添加氰化物完全抑制了Jv。向含有碳酸氢盐的管腔溶液中或在存在氯梯度的情况下添加D-葡萄糖、L-丙氨酸或两者，对Jv没有显著影响。向氯化钠-甜蜜素钠管腔溶液中添加两种有机溶质导致Jv显著升高，为0.77±0.14 nl/分钟/毫米。这些研究表明，大鼠浅表近端小管中的Jv受活性钠转运、管腔中碳酸氢盐的存在和/或跨上皮氯梯度的施加影响。有机溶质D-葡萄糖和L-丙氨酸也影响水吸收，但这种影响仅在某些实验条件下才能得到证实。
