Effect of propionate on the utilization of nitrogen from 15NH4Cl for urea synthesis in hepatocytes isolated from sheep liver

Garwacki, S; Wiechetek, M.; Karlik, Wojciech; Souffrant, Wolfgang-Bernhard; Krawielitzki, K.

doi:10.1016/0020-711x(90)90119-n

Cited by 7 publications

(2 citation statements)

References 24 publications

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“…However, the propionate concentration in the hepatic blood of our sheep ranged between 0•13 and 0•19 mM for the control and P2 animals respectively (P, 0•01) (Majdoub et al 2003). This is much lower than the propionate concentrations used in the in vitro studies; 5 mM (Garwacki et al 1990), and from 0•31 to 1•25 mM (Mutsvangwa et al 1997).…”

Section: Absorption and Utilisation Of The Nitrogenous Compounds By Tmentioning

confidence: 54%

Effects of intraruminal propionate supplementation on nitrogen utilisation by the portal-drained viscera, the liver and the hindlimb in lambs fed frozen rye grass

et al. 2003

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The influence of propionate supplementation on the splanchnic metabolism of amino acids (AA) and other N compounds and the supply of AA and NH 3 -N to the hindlimb was investigated in growing lambs. Six rumen-cannulated and multicatheterised lambs (32·2 kg) were fed frozen rye grass at 690 kJ metabolisable energy intake/d per kg average metabolic body weight. They were infused intraruminally with a salt solution (control) or with propionate solutions at 0·23 mol/l (P1) or 0·41 mol/l (P2) infused at a maximal rate of 1·68 (SD 0·057) ml/min according to a repeated Latin square design. The propionate infusion did not increase the net portal appearance of total AA (TAA)-N but increased that of some branched-chain AA (valine and to a lesser extent isoleucine). Simultaneously, the propionate treatment (especially P2) induced an increased TAA utilisation by the liver. This was due mainly to an increased (þ79 %; P,0·07) utilisation of the essential AA and particularly the branched-chain AA. A stimulation of protein synthesis in the liver is hypothesised since (1) propionate stimulated insulin secretion and (2) utilisation of non-essential AA were less influenced by the propionate treatment in the liver (except for alanine), suggesting that the AA utilised by the liver were directed towards protein synthesis rather than towards oxidation or urea synthesis. At the splanchnic level, the propionate treatment did not have any effect on the TAA, non-essential AA and essential AA, except for a net splanchnic release that was decreased for leucine (P, 0·02) and methionine (P,0·01) and increased for threonine (P,0·05). The propionate treatment did not have any effect on the hindlimb uptake of AA (essential and non-essential). As a consequence, even though the propionate treatment induced some major alterations in the splanchnic metabolism of AA, there were no changes in the net AA balance in the hindlimb (and hence probably on muscle growth). The role of the splanchnic tissues in the regulation of the AA supply to the peripheral tissues (such as muscle) therefore appears to be prominent in the regulation of muscle growth. Whether the peripheral tissues regulate their own supply by interacting with the splanchnic tissues (and especially the liver) or the liver is the only regulator of the AA supply to the muscle remains in doubt.

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Section: Absorption and Utilisation Of The Nitrogenous Compounds By Tmentioning

confidence: 54%

Effects of intraruminal propionate supplementation on nitrogen utilisation by the portal-drained viscera, the liver and the hindlimb in lambs fed frozen rye grass

et al. 2003

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“…Furthermore, in sheep infused with ammonium bicarbonate, there was only a limited requirement for additional amino acid catabolism to support the extra urea synthesis (Milano et al, 2000). In addition, the utilization of ammonia for urea synthesis in hepatocytes isolated from sheep liver was stimulated by propionate (Garwacki et al, 1990).…”

Section: Ammonia Metabolism In the Livermentioning

confidence: 99%

Ammonia and urea transport across the rumen epithelium: a review

Abdoun

Stumpff

Martens

2006

Anim. Health. Res. Rev.

133

117

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The transport of nitrogen across the rumen epithelium is characterized by absorption of ammonia from the rumen and by an influx of urea into the rumen. The transport rates of both compounds are large and exhibit wide variation. The transport of ammonia occurs in two forms: in the lipophilic form as NH3, the magnitude of which is linearly related to the pH in the ruminal fluid at pH values above 7, while at a physiological pH of 6.5 or lower, ammonia is predominantly absorbed as NH4+ via putative potassium channels in the apical membrane. The uptake of NH4+ depends on the potential difference of the apical membrane, Pda, and shows competition with K uptake. The pathway for basolateral exit of NH4+ is unknown. Hence, the relative transport rates of NH3 or NH4+ are determined by the ruminal pH according to the Henderson-Hasselbalch equation. Transport of ammonia interacts with the transport of Na and Mg mainly via changes of the intracellular pH. Urea recycling into the rumen has been known for many years and the transport across the rumen epithelium is mediated via urea transporters in the luminal and basolateral membrane of the epithelium. Transport of urea occurs by simple diffusion, but is highly variable. A significant increase of urea influx is caused by the fermentation products CO2 and short-chain fatty acids. Conversely, there is some evidence of inhibition of urea influx by ruminal ammonia. The underlying mechanisms of this modulation of urea transport are unknown, but of considerable nutritional importance, and future research should be directed to this aspect of ruminal transport.

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Preparation and properties of isolated hepatocytes from sheep

Clark

Vincent

2000

The Hepatocyte Review

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Effect of propionate on the utilization of nitrogen from 15NH4Cl for urea synthesis in hepatocytes isolated from sheep liver

Cited by 7 publications

References 24 publications

Effects of intraruminal propionate supplementation on nitrogen utilisation by the portal-drained viscera, the liver and the hindlimb in lambs fed frozen rye grass

Effects of intraruminal propionate supplementation on nitrogen utilisation by the portal-drained viscera, the liver and the hindlimb in lambs fed frozen rye grass

Ammonia and urea transport across the rumen epithelium: a review

Preparation and properties of isolated hepatocytes from sheep

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