Gross J B, Imai M, Kokko J P
J Clin Invest. 1975 Jun;55(6):1284-94. doi: 10.1172/JCI108048.
Electrical and permeability features of the distal convoluted tubule (DCT) and the cortical collecting tubule (CCT) were examined using the technique in which isolated segments of rabbit tubules were perfused in vitro. When rabbits were given a regular diet and tubules were perfused and bathed in artificial solutions simulating plasma ultrafiltrate, the potential difference (PD) was +3.7 plus or minus 1.9 mV in the CCT and -40.4 plus or minus 2.8 mV in the DCT. When rabbits were given a low sodium, high potassium diet plus i.m. deoxycorticosterone acetate (DOCA) (1 mg/kg per day), the PD in both the CCT (-30.8 plus or minus 3.9 mV) and the DCT (-33.8 plus or minus 5.5 mV) was negative. The PD in the CCT was quantitatively similar to that of diet plus DOCA when animals were given DOCA alone. The PD in both segments was inhibited by ouabain (10-minus 5 M) in the bath or by amiloride (10-minus 5 M) in the perfusate. Addition of vasopressin (200 muU/ml) to the bath caused a gradual decline of PD to zero in the CCT but failed to produce a potential response in the DCT. Osmotic water permeability was essentially zero in both segments in the absence of vasopressin. After addition of the vasopressin to the bath, osmotic water permeability in the DCT remained zero but increased to 71.9 plus or minus 25.5 X 10-minus 7 cm/s per atm in the CCT. We conclude that both segments are similar in that each possesses an electrogenic transport process but that these segments differ in that: (a) the CCT requires either exogenous or endogenous mineralocorticoid to maintain a maximal negative PD, whereas the PD in the DCT appears to be independent of mineralocorticoid effect; and (b) the CCT responds to vasopressin with a marked rise in water permeability, whereas the DCT is impermeable to water before and after addition of vasopressin.
采用体外灌注兔肾小管分离节段的技术，研究了远曲小管（DCT）和皮质集合小管（CCT）的电学和通透性特征。当给兔子喂常规饮食，并将肾小管在模拟血浆超滤液的人工溶液中进行灌注和浸泡时，CCT中的电位差（PD）为+3.7±1.9 mV，DCT中的电位差为-40.4±2.8 mV。当给兔子喂低钠、高钾饮食并肌肉注射醋酸脱氧皮质酮（DOCA）（每天1 mg/kg）时，CCT（-30.8±3.9 mV）和DCT（-33.8±5.5 mV）中的PD均为负值。当单独给动物注射DOCA时，CCT中的PD在数量上与饮食加DOCA时相似。两个节段中的PD均受到浴槽中哇巴因（10⁻⁵ M）或灌注液中阿米洛利（10⁻⁵ M）的抑制。向浴槽中加入血管加压素（200 μU/ml）导致CCT中的PD逐渐降至零，但在DCT中未产生电位反应。在没有血管加压素的情况下，两个节段的渗透水通透性基本为零。向浴槽中加入血管加压素后，DCT中的渗透水通透性仍为零，但CCT中的渗透水通透性增加至71.9±25.5×10⁻⁷ cm/s/atm。我们得出结论，两个节段的相似之处在于每个节段都具有电转运过程，但这些节段的不同之处在于：（a）CCT需要外源性或内源性盐皮质激素来维持最大的负PD，而DCT中的PD似乎与盐皮质激素效应无关；（b）CCT对血管加压素的反应是水通透性显著升高，而DCT在加入血管加压素前后对水均不通透。
