Dahlborn K
Swedish University of Agricultural Sciences, Department of Animal Physiology, Uppsala.
Q J Exp Physiol. 1987 Oct;72(4):593-600. doi: 10.1113/expphysiol.1987.sp003099.
Fluid balance was studied in four lactating goats during two 3 week periods, which included 30 h periods of food deprivation. In one period the goats were given 0.9% NaCl to drink, and in the other they were given water. Prior to food deprivation, fluid intake and urinary flow were similar in the two groups, but urinary Na+ excretion was higher in the saline-drinking goats. The plasma renin activity was depressed in saline-drinking goats, while the plasma aldosterone concentration was the same both in saline-drinking and water-drinking animals. Food deprivation depressed fluid intake and urine flow in all goats, but the reduction was more pronounced in goats drinking saline. The urinary Na+ and K+ excretion also decreased, in both groups, as did plasma Na+ concentration and osmolality. The plasma protein concentration increased in both groups, indicating that hypovolaemia had developed. The renin-angiotensin-aldosterone system (r.a.a.s.) became activated in goats drinking water, but not in the group drinking saline. It is suggested that sodium retention may have attenuated the activation of the r.a.a.s. in the latter group. The results of this study show that hyponatraemic hypovolaemia develops during starvation in lactating goats, regardless of the sodium state of the animals. The possibility that the hyponatraemic hypovolaemia is secondary to an impeded Na+ and fluid absorption from the rumen reticulum is discussed.
在两个为期3周的时间段内，对4只泌乳山羊的体液平衡进行了研究，其中包括30小时的禁食期。在一个时间段内，给山羊饮用0.9%的氯化钠溶液，在另一个时间段内，给它们饮用清水。在禁食前，两组山羊的液体摄入量和尿流量相似，但饮用盐水的山羊尿钠排泄量更高。饮用盐水的山羊血浆肾素活性降低，而饮用盐水和饮用清水的动物血浆醛固酮浓度相同。禁食使所有山羊的液体摄入量和尿流量减少，但饮用盐水的山羊减少更为明显。两组山羊的尿钠和钾排泄量以及血浆钠浓度和渗透压也都降低。两组山羊的血浆蛋白浓度均升高，表明已出现血容量不足。饮用清水的山羊肾素-血管紧张素-醛固酮系统（RAAS）被激活，但饮用盐水的组未被激活。提示钠潴留可能减弱了后一组中RAAS的激活。本研究结果表明，泌乳山羊在饥饿期间会出现低钠血症性血容量不足，与动物的钠状态无关。本文还讨论了低钠血症性血容量不足继发于瘤胃网胃钠和液体吸收受阻的可能性。
