Urea metabolism

The significance of pH is particularly interesting since pH may either augment or diminish NH3 production. The possible mechanisms by which pH affects NH3 production are (a) inhibition of bacterial metabolism, (b) pH-dependent changes in urea metabolic pathways, (c) pH-dependent bacterial utilization of glucose and urea as energy sources, and (d) increased bacterial uti-... 

MaePherson, L. M. D., and Dawes, C. (1991). Urea concentration in minor mucus gland secretions and the effect of salivary film velocity on urea metabolism by streptococcus vestibularis in an artificial plaque./Periodont. Res. 26, 395- 01. 

Segawa, K., T. Kataoka, and Y. Fukuo. Cholesterol-lowering effects of psyllium seed associated with urea metabolism. Biol Pharm Bull 1998 21(2) 184-187. 

Downard et al. reported that benzoic acid could induce cutaneous vasodilatation after topical application caused by the local formation of prostaglandin Dj in the skin [50]. Benzoic acid can be clinically used to treat hyperammonemia caused by a genetic defect in urea metabolism [48]. 

The fasting venous plasma ammonia concentration is useful in the differential diagnosis of encephalopathy when it is unclear if encephalopathy is of an hepatic origin. It is especially helpful in diagnosing Reye s syndrome and the inherited disorders of urea metabolism. However, it is not a useful test to use in patients with laiown liver disease. 

Fig. 3. Proposed relationships between urea metabolism and the production of guanidino compounds.

Harada K, Murawaki Y, Hirayama C. 1985. Comparative studies of nicotinohydroxamic acid and neomycin on ammonia and urea metabolism in rats. Res Commun Chem Pathol Pharmacol 49 309-312. 

Forist AA and Chulski T, pH-solubility relations for l-butyl-3-(p-tolylsulfonyl)urea (Orinase) and its metabolite, l-butyl-3-(p-carboxyphenylsulfonyl)urea. Metabolism, 5, 807-812 (1956). NB The metabolite was found to have pJCa = 3.54 at 37.5 °C by the solubility medrod. See also Glibenclamide for furdier discussion. See also Beyer WF, Jensen EH, Tolbutamide, APDS, 3,513-543 (1974). 

Which of the following describes the involvement of tissues in urea metabolism ... 

One product of arginase action is urea. Urea metabolism is included in this chapter because of its close relationship to the ornithine cycle. Urea is not known to be incorporated in toto into organic molecules (Bollard, 1959 Reinbothe and Mothes, 1962). Urea is metabolized in higher plants to ammonium and CO2 by urease [Eq. (12)] or in some organisms by an ATP-dependent urease [Eqs. (14) and (15), see page 389]. 

Harmeyer, J. and H. Martens, 1980. Aspects of urea metabolism in ruminants with reference to the goat. J. Dairy Sci. 

Hinderer, S. and W. von Engelhaidt, 1975. Urea metabolism in the llama. Comp. Biochem. Physiol. 52A, 619-622. Van Saun, R.J., 2006. Nutrient requirements of South American Camelids A factorial approach. Small Ruminant Res. 61, 165-186. 

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