Law R O
J Physiol. 1984 Aug;353:67-80. doi: 10.1113/jphysiol.1984.sp015322.
A study has been made of Na+ and Cl- binding in metabolically inhibited slices of rat renal cortex and outer medulla incubated in modified Krebs phosphate-bicarbonate Ringer solution. At pH 7.35 in control media (cortex, 147 mmol Na+/l, 105 mmol Cl-/l; outer medulla, 187 mmol Na+/l, 145 mmol Cl-/l) cortical slices bound (mean) 171 nmol Na+ and 56.7 nmol Cl-/mg solute-free dry weight; outer medullary slices bound 188 nmol Na+/mg and negligible amounts of Cl-. In both regions, Na+ was exchangeable on a 1:1 basis for K+ or Li+ in media containing equal concentrations of each cation: Na+ was completely displaced by La3+. In cortical slices in media containing equimolar Cl- and other monovalent anions, binding occurred according to the sequence acetate less than or equal to salicylate less than or equal to Cl- less than SCN-; Cl- was completely displaced by PO4(3-). When medium pH was lowered, Na+ binding was markedly reduced in both regions, whereas Cl- binding increased (and became significant in outer medulla). In NaCl solutions, Na+ binding capacity was saturated at control Na+ concentrations. When [Na+] was progressively reduced (iso-osmolality being maintained by addition of urea), bound Na+ in both regions was nearly linearly related to log medium [Na+]. Raising medium osmolality with urea caused decreased Na+ binding and increased Cl- binding in both regions. Na+ binding in both regions was significantly reduced by pre-treatment with chondroitinase ABC. Binding of both ions was independent of temperature within the range 2-37 degrees C. The possibility is raised that renal ionic binding might influence vectorial ion transport by affecting free ion activity in the region of the transporting cells.
对在改良的 Krebs 磷酸盐 - 碳酸氢盐林格溶液中孵育的大鼠肾皮质和外髓代谢抑制切片中的 Na⁺ 和 Cl⁻ 结合进行了研究。在对照培养基中（皮质，147 mmol Na⁺/l，105 mmol Cl⁻/l；外髓，187 mmol Na⁺/l，145 mmol Cl⁻/l），pH 为 7.35 时，皮质切片结合（平均）171 nmol Na⁺ 和 56.7 nmol Cl⁻/mg 无溶质干重；外髓切片结合 188 nmol Na⁺/mg，Cl⁻ 结合量可忽略不计。在两个区域中，在含有等浓度每种阳离子的培养基中，Na⁺ 可与 K⁺ 或 Li⁺ 以 1:1 的比例进行交换：Na⁺ 被 La³⁺ 完全取代。在含有等摩尔 Cl⁻ 和其他单价阴离子的培养基中的皮质切片中，结合按照乙酸根≤水杨酸根≤Cl⁻＜SCN⁻ 的顺序发生；Cl⁻ 被 PO₄³⁻ 完全取代。当培养基 pH 降低时，两个区域的 Na⁺ 结合均明显减少，而 Cl⁻ 结合增加（并且在外髓中变得显著）。在 NaCl 溶液中，Na⁺ 结合能力在对照 Na⁺ 浓度下达到饱和。当 [Na⁺] 逐渐降低（通过添加尿素维持等渗）时，两个区域中结合的 Na⁺ 与对数培养基 [Na⁺] 几乎呈线性关系。用尿素提高培养基渗透压会导致两个区域的 Na⁺ 结合减少和 Cl⁻ 结合增加。用软骨素酶 ABC 预处理会显著降低两个区域的 Na⁺ 结合。在 2 - 37℃ 范围内，两种离子的结合均与温度无关。由此提出一种可能性，即肾脏离子结合可能通过影响转运细胞区域的游离离子活性来影响向量离子转运。
