Total Water Content of Laboratory Animals With Special Reference to Volume of Fluid Within the Lumen of the Gastrointestinal Tract

Publisher Website
Google Scholar
Abstract
Data are presented on the magnitude of the fluid located within the gastrointestinal tract of commonly used laboratory animals and its relationship to the total body water as determined by desiccation. The amount found in the rabbit and the guinea pig may be considerable, even after prolonged fasting. Thus, the rabbit subsisting on food and water ad libitum has an intraluminal gut fluid content comprising about 15% of the total body water. Even after 48 hours of food deprivation, with access to fluid, there is no significant alteration in this relationship. At the end of 1 week of fasting, the gut fluid has decreased to about 10% of the total body water but thereafter this relationship appears to remain constant although food is deprived for 4 weeks. Guinea pigs subsisting on food and water ad libitum show sex differences in gut water content. Thus, in the female the gut water comprises about 17% of the total body water, whereas in the male it ranges about 20%. When deprived of food but allowed water, both sexes have an intraluminal gut water content which still comprises about 17% of the total body water at the end of 5 days. Deprived of both food and water, the water content of the gastrointestinal tract at the end of 5 days is above 10%. Dogs and rats show much smaller amounts of fluid within the gut. The dog after 24 hours of food deprivation but allowed access to water has a gut fluid content amounting to 3% of the total body water, a value which further decreases to about 1.4% in 48 hours. The rat allowed food and water has a gut fluid comprising 6.7% of its total body water. After 24 hours of food deprivation this has fallen to 4.6% in the female and 2.7% in the male. Incidental findings are also given for mice, hamsters, and a goat. The significance of gut water and its possible importance in body fluid measurements, is discussed.