scholarly journals Altered Nitrogen Balance and Decreased Urea Excretion in Male Rats Fed Cafeteria Diet Are Related to Arginine Availability

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
David Sabater ◽  
Silvia Agnelli ◽  
Sofía Arriarán ◽  
José-Antonio Fernández-López ◽  
María del Mar Romero ◽  
...  
Keyword(s):  
Amino Acid ◽  
Urea Cycle ◽  
Cafeteria Diet ◽  
Nitrogen Excretion ◽  
Male Rats ◽  
Synthetase Activity ◽  
Carbamoyl Phosphate Synthetase ◽  
Carbamoyl Phosphate ◽  
Urea Excretion ◽  
Dietary Nitrogen

Hyperlipidic diets limit glucose oxidation and favor amino acid preservation, hampering the elimination of excess dietary nitrogen and the catabolic utilization of amino acids. We analyzed whether reduced urea excretion was a consequence of higherNOx; (nitrite, nitrate, and other derivatives) availability caused by increased nitric oxide production in metabolic syndrome. Rats fed a cafeteria diet for 30 days had a higher intake and accumulation of amino acid nitrogen and lower urea excretion. There were no differences in plasma nitrate or nitrite.NOxand creatinine excretion accounted for only a small part of total nitrogen excretion. Rats fed a cafeteria diet had higher plasma levels of glutamine, serine, threonine, glycine, and ornithine when compared with controls, whereas arginine was lower. Liver carbamoyl-phosphate synthetase I activity was higher in cafeteria diet-fed rats, but arginase I was lower. The high carbamoyl-phosphate synthetase activity and ornithine levels suggest activation of the urea cycle in cafeteria diet-fed rats, but low arginine levels point to a block in the urea cycle between ornithine and arginine, thereby preventing the elimination of excess nitrogen as urea. The ultimate consequence of this paradoxical block in the urea cycle seems to be the limitation of arginine production and/or availability.

Functional ureogenesis in the gobiid fish Mugilogobius abei

2000 ◽  
Vol 203 (24) ◽  
pp. 3703-3715 ◽  
Author(s):  
K. Iwata ◽  
M. Kajimura ◽  
T. Sakamoto
Keyword(s):  
Loading Condition ◽  
Urea Cycle ◽  
Sea Water ◽  
Ammonia Solution ◽  
Nitrogen Excretion ◽  
Whole Body ◽  
Carbamoyl Phosphate Synthetase ◽  
Carbamoyl Phosphate ◽  
Gobiid Fish ◽  
N Enrichment

To examine the transition to ureogenesis, the gobiid fish Mugilogobius abei was immersed in 2 mmol l(−)(1) NH(4)HCO(3) or a (15)N-labelled ammonia solution [1 mmol l(−)(1) ((15)NH(4))(2)SO(4), pH 8.0] for 4–8 days. When exposed to 2 mmol l(−)(1) NH(4)HCO(3) or (15)N-labelled ammonia solution for 4 days, the rate of urea excretion increased to seven times that of the control (in 20 % synthetic sea water) and remained at this level for 4 days. The proportion of nitrogen excreted as urea reached 62 % of total nitrogen excretion (ammonia-N + urea-N). (15)N-enrichment of the amide-N in glutamine in the tissues of fish exposed to (15)N-labelled ammonia was virtually the same as that of ammonia-N: i.e. approximately twice that of urea-N in the excreta and the tissues. Glutamine contents and glutamine synthetase activities in the liver and muscle increased greatly following exposure to ammonia. Urea and citrulline contents in the muscle and whole body of the exposed fish increased significantly, whereas uric acid contents remained unchanged. Carbamoyl phosphate synthetase III (CPSase III) mRNA expression and CPSase III activity were detected in the muscle, skin and gill, but levels were negligible in the liver. Furthermore, all other ornithine-urea cycle (O-UC) enzymes were also detected in muscle, skin and gill. Thus, M. abei clearly shows the transition from ammoniotely to ureotely under ammonia-loading condition and is able to produce urea mainly via the O-UC operating in multiple non-hepatic tissues as a means for ammonia detoxification.

scholarly journals Induction of ornithine-urea cycle enzymes and nitrogen metabolism and excretion in rainbow trout (Oncorhynchus mykiss) during early life stages

1995 ◽  
Vol 198 (1) ◽  
pp. 127-135 ◽  
Author(s):  
P Wright ◽  
A Felskie ◽  
P Anderson
Keyword(s):  
Rainbow Trout ◽  
Urea Cycle ◽  
Larval Fish ◽  
Ammonia Excretion ◽  
Nitrogen Excretion ◽  
Carbamoyl Phosphate ◽  
Adult Liver ◽  
Air Exposure ◽  
Terrestrial Vertebrates ◽  
Urea Excretion

The ornithine­urea cycle (OUC) is present in elasmobranch fish and many terrestrial vertebrates. Recently, a functional OUC has been reported in a few teleost species, suggesting that all teleost fish have the genes for the OUC, but expression is relatively rare. We investigated the possibility that the OUC is expressed during early development in trout as a mechanism for detoxifying ammonia produced from the catabolism of yolk protein. We followed ammonia and urea excretion rates, tissue ammonia and urea levels and OUC enzyme activities in rainbow trout up to 93 days after fertilization. Both ammonia and urea tissue concentrations increased several-fold in the first 40 days after fertilization (embryo stage), peaking at 1.7 mmol N l-1 and 2.5 mmol N l-1, respectively. Ammonia excretion could be detected in 4-day-old embryos, but urea excretion was not initiated until after hatching (day 45). Urea excretion in larval fish (days 42­93) increased several-fold and by day 93 was 14 % of total nitrogen excretion, as found in adult trout. Glutamine synthetase (GSase) and arginase activities were detected in 'whole animal' homogenates just after hatching and the levels of activity increased markedly to day 93. Carbamoyl phosphate synthetase (CPSase) and ornithine transcarbamylase (OTCase) were first detected in 40-day-old embryos; activities peaked between days 53 and 71 and then subsequently decreased. Adult liver enzyme activity for GSase was several-fold lower than in whole larval trout and OTCase and CPSase III (glutamine- and N-acetylglutamate-dependent CPSase catalysing the first step of the OUC) activities were essentially absent in adult liver. We conclude that embryonic and larval trout are primarily ammoniotelic. Urea is synthesized immediately after fertilization, but is not excreted until after the embryo is hatched. The results provide evidence for the presence of the OUC in larval rainbow trout, since four of the OUC enzymes are induced just after hatching and the levels of activity are relatively high compared with those in adult liver tissue. Furthermore, we suggest that all teleosts have retained the OUC genes, which are expressed only during certain stages of development (embryogenesis), and in a few rare species expression is maintained throughout the life cycle to cope with unusual environmental conditions (e.g. alkaline water, air exposure).

The effect of increased absorption of ammonia and aroinine on splanchnic metabolism of beef steers

1993 ◽  
Vol 1993 ◽  
pp. 173-173
Author(s):  
S A Maltby ◽  
C K Reynolds ◽  
M A Lomax ◽  
D E Beever
Keyword(s):  
Amino Acids ◽  
Urea Cycle ◽  
Beef Steers ◽  
Carbamoyl Phosphate ◽  
Lower Efficiency ◽  
Dietary Nitrogen ◽  
Rate Limiting Step ◽  
Ammonia Conversion ◽  
Rate Limiting ◽  
Hepatic Synthesis

Cattle fed forage based diets often absorb a high proportion of dietary N as ammonia (NH3N) and this must be detoxified in the liver to urea. It has been suggested that this process utilises both energy and amino acids and may contribute to the lower efficiency of utilisation of dietary nitrogen and energy observed in forage fed ruminants (Fitch et al, 1989). However it is not known to what extent ammonia conversion to urea requires simultaneous deamination of amino acids. We report an experiment which examined hepatic nitrogen and energy metabolism at two different rates of NH3 arrival at the liver, in response an infusion of arginine to increase urea cycle flux. Arginine stimulates the hepatic synthesis of N-acetyl glutamate which is an activator of carbamoyl-phosphate synthase, the rate limiting step of the urea cycle (Meijer et al, 1990).

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

scholarly journals Adaptation of the carbamoyl-phosphate synthetase enzyme in an extremophile fish

2020 ◽  
Vol 7 (10) ◽  
pp. 201200
Author(s):  
Lewis J. White ◽  
Gemma Sutton ◽  
Asilatu Shechonge ◽  
Julia J. Day ◽  
Kanchon K. Dasmahapatra ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Convergent Evolution ◽  
Urea Cycle ◽  
Substrate Affinity ◽  
Carbamoyl Phosphate Synthetase ◽  
Carbamoyl Phosphate ◽  
Terrestrial Vertebrates ◽  
Terrestrial Vertebrate ◽  
Myogenic Lineage ◽  
Mature Fish

Tetrapods and fish have adapted distinct carbamoyl-phosphate synthase (CPS) enzymes to initiate the ornithine urea cycle during the detoxification of nitrogenous wastes. We report evidence that in the ureotelic subgenus of extremophile fish Oreochromis Alcolapia , CPS III has undergone convergent evolution and adapted its substrate affinity to ammonia, which is typical of terrestrial vertebrate CPS I. Unusually, unlike in other vertebrates, the expression of CPS III in Alcolapia is localized to the skeletal muscle and is activated in the myogenic lineage during early embryonic development with expression remaining in mature fish. We propose that adaptation in Alcolapia included both convergent evolution of CPS function to that of terrestrial vertebrates, as well as changes in development mechanisms redirecting CPS III gene expression to the skeletal muscle.

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