Lillywhite Harvey B
Department of Biology, University of Florida, Gainesville, FL 32611-8525 USA
J Exp Biol. 2017 Oct 1;220(Pt 19):3565-3570. doi: 10.1242/jeb.163725. Epub 2017 Aug 4.
An important question related to the survival of dehydrating animals is whether feeding provides a net gain of water - contributing postprandial free water and metabolic water - or, alternatively, whether digestion and assimilation of ingested food incur a net loss of water because of requirements for digestion and the excretion of resulting metabolic wastes. Here, I address the question whether voluntary drinking increases or decreases following the ingestion of food. Increased postprandial drinking implies that food consumption increases rather than decreases the requirement for free water, whereas decreased postprandial drinking suggests there is a net profit of water from food. Snakes are ideally suited for such inquiry because they feed intermittently, and the temporal separation of meals allows relatively clear examination of the associated patterns of pre- and postprandial drinking. Voluntary drinking associated with meal consumption was quantified during consecutive feeding trials in four species representing two families of snakes. Postprandial relative to preprandial drinking increased in all four species, indicating that eating increases the physiological requirement for water. These data add to a growing literature pointing to some generality that eating can have negative rather than positive consequences for fluid homeostasis in some dehydrating animals.
一个与脱水动物生存相关的重要问题是，进食是否能带来水的净增益（餐后提供游离水和代谢水），或者相反，由于消化需求以及代谢废物的排泄，摄入食物的消化和同化是否会导致水的净损失。在此，我探讨进食后自愿饮水是增加还是减少这一问题。餐后饮水增加意味着食物消耗增加了而非减少了对游离水的需求，而餐后饮水减少则表明食物中有水的净收益。蛇非常适合进行此类探究，因为它们间歇性进食，餐间的时间间隔使得相对清晰地研究餐前和餐后饮水的相关模式成为可能。在代表两个蛇科的四个物种的连续进食试验中，对与进食相关的自愿饮水进行了量化。所有四个物种餐后相对于餐前的饮水都增加了，这表明进食增加了对水的生理需求。这些数据进一步丰富了越来越多的文献，这些文献指出了一个普遍现象，即进食对一些脱水动物的液体平衡可能产生负面而非正面的影响。
