Stephens D B
Q J Exp Physiol. 1985 Jul;70(3):389-401. doi: 10.1113/expphysiol.1985.sp002924.
Eighteen young growing pigs of the Large White breed were housed in individual pens or metabolism stands and habituated to drinking their water from a bowl. Those housed in the metabolism stands were surgically fitted with a catheter placed in he jugular vein to allow collection of blood samples. The voluntary intake of water after periods of progressively increasing water deprivation was measured. The measurements were made by allowing the pigs to drink to satiety after either a 2, 4, 8, 12 or 18 h period of water deprivation. Voluntary water intake was a function of the duration of water withdrawal and the rate of intake increased with progressive deprivation. Changes in plasma concentration of sodium and protein, haematocrit and osmolality could be detected after 12 and 18 h of dehydration. The progressive changes in plasma sodium concentration ([Na+]), osmolality, protein concentration and haematocrit during adaptation to dehydration when water was withheld for 72 h were examined in six pigs. Using a technique of continuous blood sampling, the rapid changes in the same blood parameters during rehydration, when water was made freely available at the end of the 72 h period, were also monitored. The [Na+] and osmolality dropped precipitously following the onset of drinking. From the 15 min stage to the 4 h stage with water available ad libitum, the values of both parameters remained below their control levels. However, the plasma protein concentration and the haematocrit values remained significantly above their pre-dehydration control levels up to the 4 h stage, even with water freely available, thus showing that drinking stopped even though the extracellular fluid phase remained dehydrated. Only with food available did the blood measures return to normal. It is concluded that the cellular fluid phase forms an integral part of the mechanisms involved in the termination of drinking in the pig.
18头大白品种的幼年生长猪被饲养在单独的围栏或代谢笼中，并习惯从碗中饮水。饲养在代谢笼中的猪通过手术在颈静脉放置一根导管，以便采集血样。测量了在逐渐增加缺水时间后水的自愿摄入量。测量方法是让猪在缺水2、4、8、12或18小时后饮水至饱足。自愿饮水量是缺水持续时间的函数，随着缺水程度的加重，饮水速率增加。在脱水12小时和18小时后，可以检测到血浆钠、蛋白质浓度、血细胞比容和渗透压的变化。对6头猪在禁水72小时适应脱水过程中血浆钠浓度([Na+])、渗透压、蛋白质浓度和血细胞比容的逐渐变化进行了研究。使用连续采血技术，还监测了在72小时结束时自由饮水复水过程中相同血液参数的快速变化。饮水开始后，[Na+]和渗透压急剧下降。从15分钟阶段到4小时阶段自由饮水时，这两个参数的值都低于其对照水平。然而，即使自由饮水，血浆蛋白浓度和血细胞比容值在4小时阶段之前仍显著高于脱水前的对照水平，这表明即使细胞外液相仍处于脱水状态，饮水也停止了。只有在有食物的情况下，血液指标才恢复正常。结论是，细胞液相是猪饮水终止机制的一个组成部分。
