contents of the foregut of a langur accounted for 12% of live body mass, and foregut contents were 85% water.

The percentage of total body water (by tritiated-water dilution) in adult chimpanzees has been found to average 67%, slightly higher than the average in adult humans because of the lower body fat in the chimpanzees studied (9%) than in the adult humans (20%) with which they were compared (Angus, 1971). On the basis of tritiated-water dilution, comparable mean concentrations of body water (64%) were found in adult female cynomolgus (Macaca fascicularis) and rhesus (M. mulatta) macaques (Azar and Shaw, 1975).

In 13 normal male pigtailed macaques (Macaca nemestrina) with a mean age of 70 months, body water by tritium dilution was 72.6%. In 12 normal female pigtailed macaques with a mean age of 90 months, body water was 70.1%. In five obese female pigtailed macaques with a mean age of 130 months, body water was 52.5% (Walike et al., 1977).

Nonhuman primates in captivity can differ dramatically in percentage of body water and corresponding percentage of body fat—hence their degree of obesity—just as humans do. In a study of 23 adult baboons (Papio sp.), fat in 10 males was 2.4-17.6% and in 13 females 3.7-33.0% of body mass (Lewis et al., 1986). In another study, fat in 24 adult male rhesus macaques was 5.9-49.0% of body mass (Jen et al., 1985). Kemnitz and Francken (1986) also found a wide range of adiposity in adult male rhesus macaques. Body fat ranged from 30-61% of body weight and was located most prominently in the abdomen. Glucose tolerance was normal, but blood insulin concentrations and insulin response to glucose loading increased with increasing adiposity. The authors concluded that obese monkeys, like obese humans, are at risk for diabetes mellitus and its complications.

With antipyrine dilution, total body water was estimated in 16 adult nonpregnant female baboons (Papio cynocephalus) 4-14 years old and weighing 11.0-13.9 kg (Brans et al., 1985). Although mean total body water was reported to be 798 L·kg-1 of body mass, it is assumed that the authors meant 798 ml·kg-1. Thus, total body water would have been about 80% of body mass. That value is higher than expected and higher than mean values (770 and 769 ml·BWkg-1 ) reported for newborn (day 1) and 29-day-old baboons, again on the basis of the antipyrine dilution technique (Brans et al., 1986b). In a study of the effects of extracorporeal membrane oxygenation (as used in intracardiac surgery) on body water content and distribution, total body water, extracellular water, and plasma volume were measured simultaneously with antipyrine, bromide, and T-1824 (Evans blue) dilution in neonate baboons 17-28 days old and weighing 820-1,478 g (Brans et al., 1986a). Measurements were made before and after 8 hours of extracorporeal membrane oxygenation. Estimates (± SE) of antipyrine space were 843 ± 37.4 and 787 ± 80.5 ml·BWkg-1, respectively, and were not significantly different. Estimates of corrected bromide space were 361 ± 47.6 and 409 ± 47.6 ml·BWkg-1 respectively, and of plasma volume 53 ± 8.2 and 58 ± 19.2 ml·BWkg-1; and they were also not significantly different. Calculated mean volumes of intracellular water, interstitial water, and blood were 482 and 379, 308 and 350, and 84 and 95 ml·BWkg-1, respectively. When estimated with antipyrine dilution on the day of birth in newborn baboons with mean weights of 923 and 624 g, total body water volumes were 773 and 874 ml·BWkg-1 (Brans et al., 1986c). Body water content and distribution were estimated before, during, and after 32 pregnancies in baboons weighing 10-22 kg (Brans et al., 1990b). It was concluded that mean plasma volume and blood volume were higher during pregnancy than before or after. In a later study comparing H218O dilution with antipyrine dilution in neonatal baboons, Brans et al. (1990a) concluded that antipyrine dilution is of doubtful reliability for estimating total body water.

Lewis et al. (1986) measured the total body water, triacylglycerol mass, and lean body mass of 13 female and 10 male 5-year-old baboons (Papio sp.) at necropsy. Total body water was calculated as the wet weight of the baboon (body weight minus contents of the gut and bladder) minus the dry weight of the tissues and organs. Male baboons were heavier than females (20.4 kg vs 15.9 kg) and had less triacylglycerol (6.1% vs 16.9%), and more total body water (67.4% vs 64.8%) per unit of body mass.

Because of concern expressed by Sheng and Huggins (1979) that tritiated-water dilution overestimates total body water by 4-15% compared with determination with desiccation, a nuclear magnetic resonance (NMR) method was tested by Lewis et al. (1986a) on 21 18-week-old baboons (Papio sp.). Mean total body water concentration was 71% with NMR and 70% with desiccation. When another 19 young baboons were studied, estimates of total body water were higher in 16 and lower in three when determined with tritiated-water dilution than with desiccation. In a study of 10 adult male rhesus monkeys (Macaca mulatta), weighing 6.79-12.35 kg, Baer et al. (2000) found that body-water space with deuterium oxide dilution was overestimated by 10% as compared with direct determination by desiccation. Hydration of lean body mass was 71.2 ± 0.52% (mean ± SE) with a range of 67.9-77.3%.

Chwals et al. (1992) studied the utility of magnetic resonance imaging (MRI) for determination of body water with eight Macaca fascicularis. The two measures had a correlation of 0.81 (P < 0.02), and mean total body water determined with MRI was 72.1% of body mass vs 73.8% of body mass with tritiated-water dilution.

The intracellular and extracellular distribution of water and concentrations of lipid and the electrolytes sodium, potassium, and chloride in 14 tissues of six normal male

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