de Bermudez L, Windhager E E
Am J Physiol. 1975 Dec;229(6):1536-46. doi: 10.1152/ajplegacy.1975.229.6.1536.
Changes in peritubular oncotic pressure do not alter the electrical resistance of distal convoluted tubules. Transverse specific electrical resistance decreases along the distal convoluted tubule in nondiuretic rats. This drop in resistance can be at least in part accounted for by the relative increae in osmolality of late distal fluid. Osmotic gradients influence the magnitude of intercellular rather than transcellular conductance. Hyposmolality of tubular fluid leads to reduced shunting, whereas increased tubular osmolality has the opposite effect. The osmotic effect forms part of an intraepithelial positive feedback loop for sodium reabsorption in the diluting segment of the renal nephron.
肾小管周围胶体渗透压的变化不会改变远曲小管的电阻。在非利尿大鼠中，横向比电阻沿远曲小管降低。这种电阻下降至少部分可归因于远曲小管后期液体渗透压的相对增加。渗透梯度影响细胞间而非跨细胞电导的大小。肾小管液低渗导致分流减少，而肾小管液渗透压升高则有相反的效果。这种渗透效应构成了肾单位稀释段钠重吸收上皮内正反馈回路的一部分。
