Enzymes of ammonia detoxication after portacaval shunt in the rat. I. Carbamylphosphate synthetase and aspartate transcarbamylase. 1977

J P Colombo, and J Berüter, and C Bachmann, and E Peheim

At high systemic blood concentrations ammonia may be partially deviated into the pathway of pyrimidine synthesis, as has been observed in different genetic defects of the urea cycle. The portacaval shunt (PCS) rat presents an animal model to study ammonia detoxication without an underlying enzyme defect in the urea cycle. Since ammonia may induce a deviation into the pyrimidine pathway by influencing enzymatic reactions involved in this pathway, the activity of carbamylphosphate synthetase and aspartate transcarbamylase in liver as well as the excretion of orotic acid in the urine were measured in rats 10, 20 and 30 days after PCS. The results suggest that in this experimental model ammonia may be channeled into the pyrimidine pathway leading to a stimulation of the first enzymatic step and to an increased excretion of orotic acid.

UI MeSH Term Description Entries
D008099 Liver A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances. Livers
D008297 Male Males
D009929 Organ Size The measurement of an organ in volume, mass, or heaviness. Organ Volume,Organ Weight,Size, Organ,Weight, Organ
D009963 Orotic Acid An intermediate product in PYRIMIDINE synthesis which plays a role in chemical conversions between DIHYDROFOLATE and TETRAHYDROFOLATE. Potassium Orotate,Sodium Orotate,Zinc Orotate,Acid, Orotic,Orotate, Potassium,Orotate, Sodium,Orotate, Zinc
D010770 Phosphotransferases A rather large group of enzymes comprising not only those transferring phosphate but also diphosphate, nucleotidyl residues, and others. These have also been subdivided according to the acceptor group. (From Enzyme Nomenclature, 1992) EC 2.7. Kinases,Phosphotransferase,Phosphotransferases, ATP,Transphosphorylase,Transphosphorylases,Kinase,ATP Phosphotransferases
D011167 Portacaval Shunt, Surgical Surgical portasystemic shunt between the portal vein and inferior vena cava. Eck Fistula,Portacaval Anastomosis,Portacaval Shunt,Shunt, Surgical Portacaval,Surgical Portacaval Shunt,Anastomoses, Portacaval,Anastomosis, Portacaval,Fistula, Eck,Portacaval Anastomoses,Portacaval Shunts,Portacaval Shunts, Surgical,Shunt, Portacaval,Shunts, Portacaval,Shunts, Surgical Portacaval,Surgical Portacaval Shunts
D001835 Body Weight The mass or quantity of heaviness of an individual. It is expressed by units of pounds or kilograms. Body Weights,Weight, Body,Weights, Body
D002222 Carbamoyl-Phosphate Synthase (Ammonia) An enzyme that catalyzes the formation of carbamoyl phosphate from ATP, carbon dioxide, and ammonia. This enzyme is specific for arginine biosynthesis or the urea cycle. Absence or lack of this enzyme may cause CARBAMOYL-PHOSPHATE SYNTHASE I DEFICIENCY DISEASE. EC 6.3.4.16. Carbamoyl Phosphate Synthetase I,CP Synthase I,Carbamoyl-Phosphate Synthetase (Ammonia),Carbamoyl-Phosphate Synthetase I,Carbamoylphosphate Synthetase I,Carbamyl Phosphate Synthase (Ammonia),Carbamyl-Phosphate Synthase (Ammonia),Synthase I, CP,Synthetase I, Carbamoyl-Phosphate,Synthetase I, Carbamoylphosphate
D004247 DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA, Double-Stranded,Deoxyribonucleic Acid,ds-DNA,DNA, Double Stranded,Double-Stranded DNA,ds DNA
D000641 Ammonia A colorless alkaline gas. It is formed in the body during decomposition of organic materials during a large number of metabolically important reactions. Note that the aqueous form of ammonia is referred to as AMMONIUM HYDROXIDE.

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