Biliary excretion in foreign compounds. Species difference in biliary excretion

1. The biliary excretion of injected [¹⁴C]aniline, [¹⁴C]benzoic acid, 4-amino-hippuric acid and 4-acetamidohippuric acid in six or eight species of animal (rat, dog, hen, cat, rabbit, guinea pig, rhesus monkey and sheep) was studied. 2. These compounds, with molecular weights in the range 93–236, are poorly excreted in the bile in all the species examined and, in effect, there is little significant species difference in the extent of their biliary excretion. 3. Compounds of higher molecular weight (355–495) were also studied, namely succinylsulphathiazole, [¹⁴C]stilboestrol glucuronide, sulphadimethoxine N¹-glucuronide and phenolphthalein glucuronide. 4. With these compounds a clear species difference in the extent of biliary excretion was found, the rat, dog and hen being good excretors, the rabbit, guinea pig and monkey poor excretors, and the cat and sheep taking an intermediary position. 5. There was a general trend for biliary excretion to be higher in all species when the compounds were of higher molecular weight. 6. These results are discussed in their relation to species differences in drug metabolism.     

Allantoin excretion in snakes

Allantoin, which is generally regarded as absent in the excreta of snakes, has been demonstrated in the urinary deposits of 7 species of snakes by a sensitive paper chromatographic method. It appears that allantoin is the end product of purine catabolism in these animals.     

Calcium excretion in feces of ungulates

1. Fecal excretion of calcium was examined in 122 individual ungulates representing 7 species of Equidae, 3 species of Tapiridae, 3 species of Rhinocerotidae, 2 species of Elephantidae, 2 species of Hippopotamidae, 12 species of Bovidae, 2 species of Cervidae, 3 species of Camellidae and 1 species of Giraffidae. 2. Animals were fed timothy hay, a low calcium diet or alfalfa hay, a high calcium diet. 3. In a few cases oat straw or prairie hay was used instead of timothy hay. 4. Samples of feces were obtained from individuals daily for 4 days following a 20 day dietary equilibration period. 5. Feces of equids, tapirs, rhinoceros and elephants had a lower calcium concentration and a lower Ca/P ratio than feces of ruminants when the animals were fed diets of equivalent calcium content. 6. The findings suggest that the non-ruminant ungulate equids, tapirs, rhinoceros and elephants absorb a larger proportion of dietary calcium than ruminants do.     

Urinary excretion of taurine in epilepsy

Evidence that taurine (2-aminoethanesulfonic acid) is related to the epilepsies is supported by work with both experimental animals and hurmans. It may function as a neurotransmitter or modulator of neurotransmission. Investigators using an automated amino acid analyzer reported lower mean urinary taurine excretion among epileptics. However, Rao et al. reported higher taurine excretion among epileptics using an older method. Analyses of the same epileptic and control urines by both methods coupled with paper and molecular size chromatography indicate that substances in addition to taurine are co-eluted with taurine using the older method, yielding spuriously high values. The resolution of this disparity is important because the urinary excretion of taurine may reflect primarily the influence of taurine transport alleles which may be polygenic components in the idiopathic epilepsies.     

Ammonia-nitrogen excretion in Daphnia pulex

Ammonia-nitrogen excretion rates were measured in natural summer and cultured populations of Daphnia pulex from Silver Lake, Clay County, Minnesota, USA during 1973. The mean rate of ammonia-nitrogen excretion for the summer populations was 0.20 µg N animal^–1 day^–1 or 5.11 µg N mg^–1 dry body weight day^–1 (N = 80) measured at 15°, 20°, and 25°C. These rates appear to be temperature and weight dependent, but they are probably affected by factors other than temperature and dry body weight. Ammonia-nitrogen excretion rates of Daphnia pulex cultured on Chlamydomonas reinhardi yielded the following relationship with temperature: Log₁₀E = (0.061) T 1.773, where E is µg N animal^–1 day^–1 and T is temperature °C. The ammonia-nitrogen excretion on a mg^–1 dry body weight day^–1 basis was related to temperature according to the following similar expression Log₁₀E = (0.043) T + 0.153, where E is µg N mg^–1 dry body weight day^–1, and T is temperature °C. The length-weight relationship of Daphnia pulex for the summer populations (N = 1583) was log₁₀W = (0.526) Log₁₀L + 1.357, where W is weight in µg and L is length in mm.