scholarly journals Role of dexamethasone and insulin on the development of the five urea-cycle enzymes in cultured rat foetal hepatocytes

1985 ◽  
Vol 225 (1) ◽  
pp. 271-274 ◽  
Author(s):  
A Husson ◽  
M Bouazza ◽  
C Buquet ◽  
R Vaillant
Keyword(s):  
Urea Cycle ◽  
Carbamoyl Phosphate Synthetase ◽  
Argininosuccinate Synthetase ◽  
Carbamoyl Phosphate ◽  
Urea Cycle Enzymes

The activity changes of the urea-cycle enzymes were monitored in cultured foetal hepatocytes after dexamethasone and insulin treatments. Addition of dexamethasone induced the development of carbamoyl-phosphate synthetase, argininosuccinate synthetase, argininosuccinase and arginase activities as soon as day 16.5 of gestation. When insulin was added together with dexamethasone, it markedly inhibited the steroid-induced increase in carbamoyl-phosphate synthetase, argininosuccinate synthetase and argininosuccinase activities.

scholarly journals Adaptative increase of ornithine production and decrease of ammonia metabolism in rat colonocytes after hyperproteic diet ingestion

2004 ◽  
Vol 287 (2) ◽  
pp. G344-G351 ◽  
Author(s):  
Béatrice Mouillé ◽  
Véronique Robert ◽  
François Blachier
Keyword(s):  
Cell Metabolism ◽  
Carbamoyl Phosphate Synthetase ◽  
Carbamoyl Phosphate ◽  
Ammonia Metabolism ◽  
Ornithine Carbamoyl Transferase ◽  
Urea Production ◽  
Colonic Lumen ◽  
Isocaloric Diets ◽  
The One

Chronic high-protein consumption leads to increased concentrations of NH4+/NH3 in the colon lumen. We asked whether this increase has consequences on colonic epithelial cell metabolism. Rats were fed isocaloric diets containing 20 (P20) or 58% (P58) casein as the protein source for 7 days. NH4+/NH3 concentration in the colonic lumen and in the colonic vein blood as well as ammonia metabolism by isolated surface colonic epithelial cells was determined. After 2 days of consumption of the P58 diet, marked increases of luminal and colonic vein blood NH4+/NH3 concentrations were recorded when compared with the values obtained in the P20 group. Colonocytes recovered from the P58 group were characterized at that time and thereafter by an increased capacity for l-ornithine and urea production through arginase ( P < 0.05). l-Ornithine was mostly used in the presence of NH4Cl for the synthesis of the metabolic end product l-citrulline. After 7 days of the P58 diet consumption, however, the ammonia metabolism into l-citrulline was found lower ( P < 0.01) when compared with the values measured in the colonocytes recovered from the P20 group despite any decrease in the related enzymatic activities (i.e., carbamoyl-phosphate synthetase I and ornithine carbamoyl transferase). This decrease was found to coincide with a return of blood NH4+/NH3 concentration in colonic portal blood to values close to the one recorded in the P20 group. In response to increased NH4+/NH3 concentration in the colon, the increased capacity of the colonocytes to synthesize l-ornithine is likely to correspond to an elevated l-ornithine requirement for the elimination of excessive blood ammonia in the liver urea cycle. Moreover, in the presence of NH4Cl, colonocytes diminished their synthesis capacity of l-citrulline from l-ornithine, allowing a lower cellular utilization of this latter amino acid. These results are discussed in relationship with an adaptative process that would be related to both interorgan metabolism and to the role of the colonic epithelium as a first line of defense toward luminal NH4+/NH3 concentrations.

scholarly journals Mice deficient in the urea-cycle enzyme, carbamoyl phosphate synthetase i, die during the early neonatal period from hyperammonemia

Hepatology ◽  
1999 ◽  
Vol 29 (1) ◽  
pp. 181-185 ◽  
Author(s):  
J. Paul Schofield ◽  
J. Paul Schofield ◽  
Timothy M. Cox ◽  
C. Thomas Caskey ◽  
Maki Wakamiya
Keyword(s):  
Urea Cycle ◽  
Neonatal Period ◽  
Carbamoyl Phosphate Synthetase ◽  
Carbamoyl Phosphate ◽  
Cycle Enzyme ◽  
Early Neonatal Period ◽  
Urea Cycle Enzyme

scholarly journals SIRT5 Deacetylates Carbamoyl Phosphate Synthetase 1 and Regulates the Urea Cycle

Cell ◽  
2009 ◽  
Vol 137 (3) ◽  
pp. 560-570 ◽  
Author(s):  
Takashi Nakagawa ◽  
David J. Lomb ◽  
Marcia C. Haigis ◽  
Leonard Guarente
Keyword(s):  
Urea Cycle ◽  
Carbamoyl Phosphate Synthetase ◽  
Carbamoyl Phosphate ◽  
Carbamoyl Phosphate Synthetase 1
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