Kleinman L I, Banks R O
Am J Physiol. 1980 Dec;239(6):F589-94. doi: 10.1152/ajprenal.1980.239.6.F589.
The natriuretic effect of oxytocin was studied in 40 anesthetized newborn dogs 2-33 days of age. After saline expansion, puppies excreted only 2.86% of the filtered sodium (adult dogs undergoing similar volume expansion excrete about 65-8% of the filtered sodium). After oxytocin was infused in these saline-expanded puppies at 8 mU x kg-1 x h-1, fractional sodium excretion increased to 7.51%. Oxytocin had no natriuretic effect in nonexpanded puppies. In nonexpanded animals, when distal nephron function was blocked by a combination of ethacrynic acid, chlorothiazide, and amiloride, fractional sodium excretion averaged 31%. In contrast, distal nephron blockade in saline-expanded animals resulted in fractional sodium excretion of 55%. When oxytocin was infused in either saline-expanded or nonexpanded puppies undergoing distal nephron blockade, there was no increase in sodium excretion. These results support the following conclusions. In the newborn dog 1) the attenuated natriuretic response to saline expansion is related to increased reabsorption of sodium in the distal nephron; 2) an adult type of natriuretic response to saline expansion can be induced in puppies by infusion of oxytocin; and 3) oxytocin inhibits sodium reabsorption in the distal nephron.
在40只2至33日龄的麻醉新生犬中研究了催产素的利钠作用。在生理盐水扩容后，幼犬仅排泄滤过钠的2.86%（经历类似容量扩张的成年犬排泄滤过钠的约65 - 8%）。在这些经生理盐水扩容的幼犬中以8 mU×kg-1×h-1的速度输注催产素后，钠排泄分数增加到7.51%。催产素对未扩容的幼犬没有利钠作用。在未扩容的动物中，当用依他尼酸、氯噻嗪和阿米洛利联合阻断远端肾单位功能时，钠排泄分数平均为31%。相比之下，在经生理盐水扩容的动物中阻断远端肾单位导致钠排泄分数为55%。当在经历远端肾单位阻断的经生理盐水扩容或未扩容的幼犬中输注催产素时，钠排泄没有增加。这些结果支持以下结论。在新生犬中：1）对生理盐水扩容的利钠反应减弱与远端肾单位钠重吸收增加有关；2）通过输注催产素可在幼犬中诱导出成年型对生理盐水扩容的利钠反应；3）催产素抑制远端肾单位的钠重吸收。
