Ermittlung von N-Stoffwechselparametern im N-Steigerungsversuch an der Ratte unter Verwendung von<sup>15</sup>N-Tracern

Methodical recommendations are suggested--predominantly for laboratory and small animals (rats and young chickens)--for the determination of parameters of the protein metabolism of the whole body after single doses of a mixture of 15N labelled amino acids by means of the determination of the temporal course of cumulative 15N excretion in urine and the assessment of the tracer kinetic data in a compartment model. These recommendations are to make it possible to carry out purposefully such experiments under comparable conditions. The advantages of this method are: the non-invasive character of the method; the possibility of repeating the experiment with the same animal; the adaptability to other methods of investigation (e.g. measuring energy metabolism); the relatively low expenditure of labour and requirement of test animals; the relatively good reproducibility of the method. Thus this method is a good supplement to the flooding and permanent infusion methods and should be used wherever the determination of parameters of the protein metabolism of the total body is sufficient.

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Methodische Empfehlungen zur Bestimmung von Gesamtkörper-Proteinsyntheseraten im Tracerversuch

Krawielitzki

Schadereit

Wünsche

1989

Archiv für Tierernaehrung

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Bestimmung von kinetischen Parametern des Proteinmetabolismus bei wachsenden Ratten in Verbindung mit Energieumsatzmessungen. 1. Mitteilung. Bestimmung von kinetischen Parametern des Proteinmetabolismus in Abhängigkeit von der Lebendmasse und dem Proteingehalt des Futters

Krawielitzki

Schadereit

Klein

et al. 1991

Archiv für Tierernaehrung

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The digestibility, the N balance, the rate of protein synthesis and other parameters, characterising the protein metabolism in dependence on live weight, protein- and energy supply are estimated on Wistar rats (4-5 animals/group). These experiments were done in 5 alternating consecutive growth and energy maintenance periods at 4 different levels of protein (6, 10, 17, 26% CP) during the live weight period of 70 to 230 g. The rate of protein synthesis was calculated from the course of renale 15N excretion by means of the end product method after giving a single dose of a mixture of 17 15N labelled amino acids. N deposition, rate of protein synthesis and flux rate increased with the protein level of the ration. During maintenance these data were much lower, but showed the same dependence on the protein level. The absolute protein synthesis (g/d) increased up to the live weight of 130... 180 g and decreased afterwards according to the age. The reutilization rate varied between 44 and 87% and decreased with increasing dietary protein level by 27% and during proceeding age by 8 ... 12%. In contrast to the absolute metabolism rates (g/d) the fractional rates (%/d) clearly decreased with the age of the animals. The stimulation of these rates by the dietary protein level resembled that for the absolute rates of synthesis. The protein deposition showed the typical course of a growing curve according to the N intake and the protein synthesis showed practically the same course but on a higher level. The break down remained constantly (approximately 140 mg N/d) up to an N intake of about 360 mg and afterwards it increased too.

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Bestimmung von kinetischen Parametern des Proteinmetabolismus bei wachsenden Ratten in Verbindung mit Energieumsatzmessungen. 2. Mitteilung. Bestimmung des Energiebedarfs für den Proteinansatz in Verbindung mit Messungen der Proteinsyntheserate auf unterschiedlichen Niveaus der Proteinversorgung

Klein

Hoffmann

Krawielitzki

et al. 1991

Archiv für Tierernaehrung

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Energy metabolism-by means of indirect calorimetry-and kinetic parameters of the protein metabolism on the basis of the 3-compartment model were measured with 4 groups of 4 or 5 male Wistar rats in the growth range of between 70 and 230 g live weight in a total of 5 alternately successive periods at the feeding levels growth and energy maintenance as well as 4 different levels of protein supply (6, 10, 17 and 26% crude protein in the feed). The partial energy requirement values for protein retention (bp) for every animal and every period are calculated from the data of energy metabolism. On an average of the 3 growth periods they amounted to 1.75 +/- 0.37 kJ/kJ. A statistically significant linear relation with a slope of approximately 1 could be derived regressively between the protein synthesis rate and the protein retention rate, including all 5 test periods. There was no proven relation between the bp values and the corresponding individual values of the ratio of protein synthesis rate-diminished by the regressively derived protein synthesis rate in the N balance-to the protein retention rate. The results do not permit proven statements on the quantitative relations between protein turnover and energy requirement for protein retention, which is first of all due to methodical shortcomings in measuring both protein metabolism and energy metabolism. They indicate, however, that the heat production from protein synthesis has only a relatively low share in the additional energy expenditure for protein retention and does not considerably surpass the necessary minimal cost for the synthesis of the deposited protein in growing rats.

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Ermittlung von N-Stoffwechselparametern im N-Steigerungsversuch an der Ratte unter Verwendung von¹⁵N-Tracern

Cited by 4 publications

References 26 publications

Methodische Empfehlungen zur Bestimmung von Gesamtkörper-Proteinsyntheseraten im Tracerversuch

Methodische Empfehlungen zur Bestimmung von Gesamtkörper-Proteinsyntheseraten im Tracerversuch

Bestimmung von kinetischen Parametern des Proteinmetabolismus bei wachsenden Ratten in Verbindung mit Energieumsatzmessungen. 1. Mitteilung. Bestimmung von kinetischen Parametern des Proteinmetabolismus in Abhängigkeit von der Lebendmasse und dem Proteingehalt des Futters

Bestimmung von kinetischen Parametern des Proteinmetabolismus bei wachsenden Ratten in Verbindung mit Energieumsatzmessungen. 2. Mitteilung. Bestimmung des Energiebedarfs für den Proteinansatz in Verbindung mit Messungen der Proteinsyntheserate auf unterschiedlichen Niveaus der Proteinversorgung

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Ermittlung von N-Stoffwechselparametern im N-Steigerungsversuch an der Ratte unter Verwendung von15N-Tracern

Cited by 4 publications

References 26 publications

Methodische Empfehlungen zur Bestimmung von Gesamtkörper-Proteinsyntheseraten im Tracerversuch

Methodische Empfehlungen zur Bestimmung von Gesamtkörper-Proteinsyntheseraten im Tracerversuch

Bestimmung von kinetischen Parametern des Proteinmetabolismus bei wachsenden Ratten in Verbindung mit Energieumsatzmessungen. 1. Mitteilung. Bestimmung von kinetischen Parametern des Proteinmetabolismus in Abhängigkeit von der Lebendmasse und dem Proteingehalt des Futters

Bestimmung von kinetischen Parametern des Proteinmetabolismus bei wachsenden Ratten in Verbindung mit Energieumsatzmessungen. 2. Mitteilung. Bestimmung des Energiebedarfs für den Proteinansatz in Verbindung mit Messungen der Proteinsyntheserate auf unterschiedlichen Niveaus der Proteinversorgung

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Ermittlung von N-Stoffwechselparametern im N-Steigerungsversuch an der Ratte unter Verwendung von¹⁵N-Tracern