Martino J A, Earley L E
J Clin Invest. 1967 Jul;46(7):1229-38. doi: 10.1172/JCI105616.
Anesthetized dogs receiving an infusion of chlorothiazide and ethacrynic acid were given 600-ml infusions of distilled water or dilute dextrose solutions. The absolute rate of tubular sodium reabsorption was depressed, and the glomerular filtration rate was increased during the water loading, despite the associated decreases in plasma sodium concentration and decreases in the filtered load of sodium. The extent to which fractional sodium reabsorption decreased and the excretion of sodium increased was inversely related to the degree to which the filtered load of sodium was depressed as a result of the decreased plasma sodium concentration. We conclude that, in the presence of the diuretic blockade of distal tubular sodium reabsorption, infusion of water depresses proximal tubular reabsorption of sodium and that these changes are qualitatively similar to those previously observed during infusions of saline. Similar depression of tubular reabsorption of sodium and increased excretion of sodium occurred during water loading in the absence of diuretics in dogs undergoing saline diuresis, which presumably provided a high rate of distal sodium reabsorption before water loading. We suggest that volume expansion with water depresses proximal tubular reabsorption of sodium in a manner qualitatively similar to infusions of saline and that the extent to which sodium excretion is increased during water loading is dependent upon 1) the absolute extent to which proximal reabsorption is depressed, 2) the extent to which the filtered load of sodium is maintained in the presence of a falling concentration of sodium in plasma, and 3) the extent to which increased distal reabsorption compensates for the depressed proximal reabsorption of sodium. Mechanisms are suggested whereby the previously reported inverse relationship between plasma concentration of sodium and over-all tubular reabsorption of sodium may be only apparent, and could be the result of physiologic "glomerulotubular balance" during the specific experimental maneuvers.
给接受氯噻嗪和依他尼酸输注的麻醉犬输注600毫升蒸馏水或稀释葡萄糖溶液。尽管血浆钠浓度和滤过钠负荷降低，但在水负荷期间，肾小管钠重吸收的绝对速率降低，肾小球滤过率增加。钠重吸收分数降低和钠排泄增加的程度与由于血浆钠浓度降低导致的滤过钠负荷降低程度呈负相关。我们得出结论，在远曲小管钠重吸收的利尿剂阻断存在的情况下，输注水会抑制近曲小管钠重吸收，并且这些变化在性质上与先前在输注生理盐水期间观察到的变化相似。在进行盐利尿的犬中，在没有利尿剂的情况下进行水负荷时，也发生了类似的肾小管钠重吸收抑制和钠排泄增加，这可能在水负荷前提供了较高的远曲小管钠重吸收速率。我们认为，用水进行容量扩张以与输注生理盐水在性质上相似的方式抑制近曲小管钠重吸收，并且在水负荷期间钠排泄增加的程度取决于：1）近曲小管重吸收被抑制的绝对程度；2）在血浆钠浓度下降的情况下滤过钠负荷维持的程度；3）远曲小管重吸收增加补偿近曲小管钠重吸收降低的程度。有人提出了一些机制，据此先前报道的血浆钠浓度与钠的总体肾小管重吸收之间的负相关关系可能只是表面现象，并且可能是特定实验操作期间生理“球管平衡”的结果。
