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Influence of hepatic ammonia removal on ureagenesis, amino acid utilization and energy metabolism in the ovine liver

Published online by Cambridge University Press:  09 March 2007

G. D. Milano ,
A. Hotston-Moore  and
G. E. Lobley
G. D. Milano*
Affiliation:
Facultad de Ciencias Veterinarias, Universidad Nacional del Centro (UNCPBA), Campus Universitario (7000), Tandil, Argentina
A. Hotston-Moore
Affiliation:
Rowett Research Institute, Greenburn Road, Bucksburn, Aberdeen AB21 9SB, UK
G. E. Lobley
Affiliation:
Rowett Research Institute, Greenburn Road, Bucksburn, Aberdeen AB21 9SB, UK
*
*Corresponding author: Dr Guillermo D. Milano, fax +54 2293 426667, email [email protected]
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Abstract

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The mass transfers of O2, glucose, NH3, urea and amino acids across the portal-drained viscera (PDV) and the liver were quantified, by arterio–venous techniques, during the last 4 h of a 100 h infusion of 0 (basal), 150 or 400 μmol NH4HCO3/min into the mesenteric vein of three sheep given 800 g grass pellets/d and arranged in a 3 × 3 Latin-square design. Urea irreversible loss rate (ILR) was also determined by continuous infusion of [14C]urea over the last 52 h of each experimental period. PDV and liver movements of glucose, O2 and amino acids were unaltered by NH4HCO3 administration, although there was an increase in PDV absorption of non-essential amino acids (P = 0·037) and a trend for higher liver O2 consumption and portal appearance of total amino acid-N, glucogenic and non-essential amino acids at the highest level of infusion. PDV extraction of urea-N (P = 0·015) and liver removal of NH3 (P < 0·001), release of urea-N (P = 0·002) and urea ILR (P = 0·001) were all increased by NH4HCO3 infusion. Hepatic urea-N release (y) and NH3 extraction(x) were linearly related (R2 0·89), with the slope of the regression not different from unity, both for estimations based on liver mass transfers (1·16; SE 0·144; PB ≠ 1 = 0·31) AND [14C]UREA (0·97; se 0·123; Pb ≠ 1 = 0·84). The study indicates that a sustained 1·5 or 2·4-fold increase in the basal NH3 supply to the liver did not impair glucose or amino acid supply to non-splanchnic tissues; nor were additional N inputs to the ornithine cycle necessary to convert excess NH3 to urea. Half of the extra NH3 removed by the liver was, apparently, utilized by periportal glutamate dehydrogenase and aspartate aminotransferase for sequential glutamate and aspartate synthesis and converted to urea as the 2-amino moiety of aspartate.

Keywords

SheepLiverAmmoniaUreagenesis
Type
Research Article
Information
British Journal of Nutrition , Volume 83 , Issue 3 , March 2000 , pp. 307 - 315
Copyright
Copyright © The Nutrition Society 2000

References

Agricultural and Food Research Council (1993) Energy and Protein Requirements of Ruminants. Wallingford: Commonwealth Agricultural Bureaux.Google Scholar
Arai, T, Washizu, T, Sagara, M, Sako, T, Nigi, H, Matsumoto, H, Sasaki, M and Tomoda, I (1995) D-Glucose transport and glycolytic enzyme activities in erythrocytes of dogs, pigs, cats, horses, cattle and sheep. Research in Veterinary Science 58, 195–196.Google Scholar
Barej, W, Ostaszewski, P and Pierzynowski, G (1987) Urea and glucose formation in ovine liver after ammonia and lactate loading in vivo. Annales de Recherches Veterinaires 18, 29–34.Google ScholarPubMed
Bartels, H and Harms, H (1959) Sauerstoffdissoziationskurven des Blutes von Säugetieren (Blood O2 dissociation curves in mammals). Pflügers Archiv 268, 334–365.Google Scholar
Bergmeyer, HU (1985) D-Glucose determination. Colorimetric methods with GOD and POD. In Methods of Enzymatic Analysis, vol. VI. Metabolites 1: Carbohydrates, pp. 178–185. Weinheim: VCH Verlagsgesellschaft.Google Scholar
Boon, L, Blommaart, JE, Meijer, AJ, Lamers, WH and Schoolwerth, AC (1994) Acute acidosis inhibits liver amino acid transport. No primary role for the urea cycle in acid–base balance. American Journal of Physiology 36, F1015–F1020.Google Scholar
Brosnan, JT, Brosnan, ME, Charron, R and Nissim, I (1996) A mass isotopomer study of urea and glutamine synthesis from 15N-labelled ammonia in the perfused rat liver. Journal of Biological Chemistry 271, 16199–16207.Google Scholar
Calder, AG and Smith, A (1988) Stable isotope ratio analysis of leucine and ketoisocaproic acid in blood plasma by gas chromatography/mass spectrometry. Use of the tertiary butyldimethylsilyl derivatives. Rapid Commumications in Mass Spectrometry 2, 14–16.CrossRefGoogle ScholarPubMed
Goetsch, AL, Ferrel, CL and Freetly, HC (1996) Effects of different supplements on splanchnic oxygen consumption and net fluxes of nutrients in sheep consuming bromegrass (Bromus inermis) hay. ad libitum. British Journal of Nutrition 72, 701–712.Google Scholar
Huntington, GB (1986) Uptake and transport of non protein nitrogen by the ruminant gut. Federation Proceedings 45, 2272–2276.Google Scholar
Huntington, GB (1989) Hepatic urea synthesis and site and rate of urea removal from blood of beef steers fed alfalfa hay or a high concentrate diet. Canadian Journal of Animal Science 69, 215–223.Google Scholar
Kelman, GR (1966) Digital computer subroutine for the conversion of oxygen tension into saturation. Journal of Applied Physiology 21, 1375–1376.Google Scholar
Lescoat, P, Sauvant, D and Danfær, A (1996) Quantitative aspects of blood and amino acid flows in cattle. Reproduction Nutrition et Développement 36, 137–174.Google Scholar
Lobley, GE (1994) Nutritional and endocrine regulation of energy metabolism. In Proceedings of the 13th Symposium on Energy Metabolism of Farm Animals, pp. 139–149 [Aguilera, JF, editor]. Mojácar: CSIC Publishing Service.Google Scholar
Lobley, GE, Connell, A, Lomax, MA, Brown, DS, Milne, E, Calder, AG and Farningham, DAH (1995) Hepatic detoxification of ammonia in the ovine liver: possible consequences for amino acid catabolism. British Journal of Nutrition 73, 667–685.Google Scholar
Lobley, GE, Connell, A, Revell, DK, Bequette, BJ, Brown, DS and Calder, AG (1996) Splanchnic-bed transfers of amino acids in sheep blood and plasma, as monitored through the use of a multiple U-13C-labelled amino acid mixture. British Journal of Nutrition 75, 217–235.CrossRefGoogle ScholarPubMed
Lobley, GE, Weijs, PJM, Connell, A, Calder, AG, Brown, DS and Milne, E (1996) The fate of absorbed and exogenous ammonia as influenced by forage or forage–concentrate diets in growing sheep. British Journal of Nutrition 76, 231–248.CrossRefGoogle ScholarPubMed
Luo, QJ, Maltby, SA, Lobley, GE, Calder, AG and Lomax, MA (1995) The effect of amino acids on the metabolic fate of 15NH4Cl in isolated sheep hepatocytes. European Journal of Biochemistry 228, 912–917.CrossRefGoogle ScholarPubMed
Maltby, SA, Lomax, MA, Beever, DE & Pippard, CJ (1991) The effect of increased ammonia and amino acid supply on postprandial portal-drained viscera and hepatic metabolism in growing steers fed maize silage. In Energy Metabolism of Farm Animals. Proceedings of the 12th Symposium, pp. 20–23 [Wenk, C, and Boessinger, M, editors]. Zurich: European Association for Animal Production.Google Scholar
Margaria, R (1963) A mathematical treatment of the blood dissociation curve for oxygen. Clinical Chemistry 9, 745–762.CrossRefGoogle Scholar
Marsh, WH, Fingerhut, B and Miller, H (1965) Automated and manual direct methods for the determination of blood urea. Clinical Chemistry 2, 624–627.Google Scholar
Martinrequero, A, Cipres, G, Gonzalezmanchón, C and Ayuso, MS (1993) Interrelationships between ureogenesis and gluconeogenesis in perfused rat liver. Biochimica et Biophysica Acta 1158, 166–174.Google Scholar
May, RC, Masud, T, Logue, B, Bailey, J and England, B (1992) Chronic metabolic acidosis accelerates whole body proteolysis and oxidation in awake rats. Kidney International 41, 1535–1542.CrossRefGoogle ScholarPubMed
Milano, GD (1994) Consequences of ammonia metabolism across splanchnic tissues in fasted sheep. MSc Thesis, University of Aberdeen.Google Scholar
Milano, GD (1997) Liver N transactions in sheep (Ovis aries). PhD Thesis, University of Aberdeen.Google Scholar
Mondzac, A, Erlich, GE and Seegmiller, JE (1965) An enzymatic determination of ammonia in biological fluids. Journal of Laboratory and Clinical Medicine 66, 526–531.Google Scholar
Morris, SM Jr (1992) Regulation of enzymes of urea and arginine synthesis. Annual Review of Nutrition 12, 81–101.Google Scholar
Nissim, I, Cattano, C, Nissim, I and Yudkoff, M (1992) Relative role of the glutaminase, glutamate dehydrogenase, and AMP-deaminase pathways in hepatic ureagenesis: studies with 15N. Archives of Biochemistry and Biophysics 292, 393–401.Google Scholar
Orzechowsky, A, Pierzynowski, S, Motyl, T and Barej, W (1988) Net hepatic metabolism of ammonia, propionate and lactate in sheep in relation to gluconeogenesis and ureogenesis. Journal of Animal Physiology and Animal Nutrition 59, 113–122.Google Scholar
Parker, DS, Lomax, MA, Seal, CJ and Wilton, JC (1995) Metabolic implications of ammonia production in the ruminant. Proceedings of the Nutrition Society 54, 549–563.Google Scholar
Reaich, D, Channon, SM, Scrimgeour, CM and Goodship, THJ (1992) Ammonium chloride-induced acidosis increases protein breakdown and amino acid oxidation in humans. American Journal of Physiology 263, E735–E739.Google Scholar
Reynolds, CK (1992) Metabolism of nitrogenous compounds by the ruminant liver. Journal of Nutrition 122, 850–854.Google Scholar
Reynolds, CK, Tyrrell, HF and Reynolds, PJ (1991) Effect of diet forage-to-concentrate ratio and intake on energy metabolism in growing heifers: net nutrient metabolism by visceral tissues. Journal of Nutrition 121, 1004–1015.Google Scholar
Rodríguez, NR, Miles, JM, Schwenk, W and Haymond, MW (1989) Effects of acute metabolic acidosis and alkalosis on leucine metabolism in conscious dogs. Diabetes 38, 847–853.CrossRefGoogle ScholarPubMed
Saheki, T (1972) The studies on regulatory conditions of urea synthesis using isolate perfused rat liver. 2. Urea synthesis in the rat liver subjected to different dietary conditions. Shikoku Acta Medica 28, 292–298.Google Scholar
Seal, CJ and Reynolds, CK (1993) Nutritional implications of gastrointestinal and liver metabolism in ruminants. Nutrition Research Reviews 6, 185–208.CrossRefGoogle ScholarPubMed
Weekes, TE, Richardson, RI and Geddes, N (1978) The effect of ammonia on gluconeogenesis by isolated sheep liver cells. Proceedings of the Nutrition Society 38, 3A.Google Scholar