Marchand G R, Ott C E, Cuche J L, Knox F G
J Appl Physiol. 1976 Jun;40(6):1009-11. doi: 10.1152/jappl.1976.40.6.1009.
Previous studies in rats have demonstrated that the concentration of chloride in proximal tubule fluid is greater than that in plasma. The gradient reaches a free-flow steady-state level in the early proximal tubule and is maintained throughout the accessible proximal tubule. On the other hand, studies in dogs are in conflict regarding either the existence of a gradient or the development of a free-flow steady-state level. Since a species difference of tubule fluid to plasma chloride (TF/PC1) may exist, the present study was done to systematically compare the tubule fluid to ultrafiltrate chloride ratio (TF/UFC1) in hydropenic rats and dogs during normal acid-base balance. Chloride was analyzed by microelectrometric titration. In the rat the TFC1 and UFC1 concentrations were 139 +/- 1.4 and 120 +/- 1.2 meq/1, respectively. In the dog the TFC1 and UFC1 concentrations were 138 +/- 1.3 and 121 +/- 1.5 meq/1, respectively. Thus, there was no significant difference in the TF/UFC1 ratio between the rat (1.17 +/- 0.02) and the dog (1.14 +/- 0.01). Furthermore, regression analysis indicates that there is no correlation between TF/UFC1 and TF/PIn in either the rat or dog, which suggests that the gradient originates early in the proximal tubule and is maintained throughout the accessible proximal tubule in both species.
先前对大鼠的研究表明，近端小管液中的氯离子浓度高于血浆中的氯离子浓度。该梯度在近端小管起始段达到自由流动稳态水平，并在整个可检测的近端小管中维持。另一方面，关于狗的研究在梯度的存在或自由流动稳态水平的发展方面存在矛盾。由于小管液与血浆氯离子（TF/PC1）可能存在种属差异，因此进行本研究以系统比较禁水大鼠和狗在正常酸碱平衡期间小管液与超滤液氯离子的比率（TF/UFC1）。氯离子通过微电极滴定法进行分析。大鼠的TFCl和UFC1浓度分别为139±1.4和120±1.2 meq/1。狗的TFCl和UFC1浓度分别为138±1.3和121±1.5 meq/1。因此，大鼠（1.17±0.02）和狗（1.14±0.01）之间的TF/UFC1比率没有显著差异。此外，回归分析表明，大鼠和狗的TF/UFC1与TF/PIn之间均无相关性，这表明该梯度在近端小管起始段形成，并在两个物种的整个可检测近端小管中维持。
