Effects of in vitro addition of ammonia on the metabolism of 15N-labelled amino acids in isolated sheep hepatocytes
| Autor: | Timothy Mutsvangwa, Brian W. McBride, J. G. Buchanan-Smith |
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| Rok vydání: | 1999 |
| Předmět: | |
| Zdroj: | Canadian Journal of Animal Science. 79:321-326 |
| ISSN: | 1918-1825 0008-3984 |
| DOI: | 10.4141/a98-082 |
| Popis: | Isolated hepatocytes prepared from sheep were used to determine the effects of added ammonia (as NH4Cl) on the flux of 15N from 15N-labelled amino acids to [14N15N]urea and [15N15N]urea. Hepatocyte suspensions were incubated with NH4Cl (0, 0.31, 0.63 and 1.25 mM) in the presence of L-[15N]alanine, L-[15N]methionine, L-[15N]leucine or L-[15N]phenylalanine (1.0 mM final concentration in the incubation media). Following 1.5 h incubation, addition of NH4Cl increased total urea and unlabelled (14N14N) urea production in all incubations (P 4Cl did not affect 15N isotopic enrichment of [14N15N]urea (P = 0.705) and [15N15N]urea (P = 0.204), or production of [14N15N]urea (P = 0.279) and [15N15N]urea (P = 0.708) in isolated hepatocytes incubated with [15N]alanine. Addition of NH4Cl increased [14N15N]urea production in incubations containing [15N]methionine (quadratic effect, P = 0.019), but had no effect in incubations containing [15N]leucine (P = 0.107) or [15N]phenylalanine (P = 0.135). There was no detectable production of [15N15N]urea in incubations containing [15N]methionine, [15N]leucine and [15N]phenylalanine. In all incubations, unlabelled (14N14N) urea was the predominant form of urea, indicating that isolated sheep hepatocytes can detoxify excess NH3 by channelling NH3-N into both mitochondrial carbamoyl phosphate and cytoplasmic aspartate synthesis. Key words: Sheep, liver cells, amino acids, ureagenesis, ammonia, 15N |
| Databáze: | OpenAIRE |
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