Altered nitrogen balance and decreased urea excretion in male rats fed cafeteria diet are related to arginine availability.
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 higher NO x ; (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. NO(x) and 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.
Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, 08028 Barcelona, Spain ; Institute of Biomedicine, University of Barcelona, 08028 Barcelona, Spain.
David
D
Sabater
Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, 08028 Barcelona, Spain ; Institute of Biomedicine, University of Barcelona, 08028 Barcelona, Spain.
Silvia
0000-0002-6596-1318
S
Agnelli
Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, 08028 Barcelona, Spain ; Institute of Biomedicine, University of Barcelona, 08028 Barcelona, Spain.
Sofía
S
Arriarán
Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, 08028 Barcelona, Spain ; Institute of Biomedicine, University of Barcelona, 08028 Barcelona, Spain ; CIBER Obesity and Nutrition, Institute of Health Carlos III, 28029 Madrid, Spain.
José-Antonio
JA
Fernández-López
Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, 08028 Barcelona, Spain ; Institute of Biomedicine, University of Barcelona, 08028 Barcelona, Spain ; CIBER Obesity and Nutrition, Institute of Health Carlos III, 28029 Madrid, Spain.
María del Mar
Mdel M
Romero
Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, 08028 Barcelona, Spain ; Institute of Biomedicine, University of Barcelona, 08028 Barcelona, Spain ; CIBER Obesity and Nutrition, Institute of Health Carlos III, 28029 Madrid, Spain.
Marià
0000-0002-9783-8293
M
Alemany
Department of Nutrition and Food Science, Faculty of Biology, University of Barcelona, 08028 Barcelona, Spain ; Institute of Biomedicine, University of Barcelona, 08028 Barcelona, Spain ; CIBER Obesity and Nutrition, Institute of Health Carlos III, 28029 Madrid, Spain.
Xavier
X
Remesar
D000818:Animals; D001120:Arginine / Q000096:biosynthesis / Q000378:metabolism*; D004032:Diet; D008297:Male; D009584:Nitrogen / Q000378:metabolism*; D009952:Ornithine / Q000378:metabolism; D051381:Rats; D065667:Renal Elimination / Q000502:physiology; D014508:Urea / Q000378:metabolism*
D014508:Urea; D001120:Arginine; D009952:Ornithine; D009584:Nitrogen