Effects of long-term protein excess or deficiency on whole-body protein turnover in sheep nourished by intragastric infusion of nutrients
| Autor: | Gerald Lobley, N. A. Macleod, S. M. Liu, D. J. Kyle, E. R. Ørskov, X. B. Chen |
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| Rok vydání: | 1995 |
| Předmět: |
Male
medicine.medical_specialty Time Factors Nitrogen Medicine (miscellaneous) Biology chemistry.chemical_compound Enteral Nutrition Nutrient Volatile fatty acids Ammonia Protein Deficiency Casein Internal medicine medicine Animals Urea Sheep Nutrition and Dietetics Body Weight Protein turnover Proteins Metabolism Endocrinology chemistry Dietary Proteins Leucine Whole body |
| Zdroj: | British Journal of Nutrition. 73:829-839 |
| ISSN: | 1475-2662 0007-1145 |
| Popis: | The effect of long-term dietary protein excess and deficit on whole-body protein-N turnover (WBPNT) was examined in lambs nourished by intragastric infusions of nutrients. Ten sheep were given 500 mg N/kg metabolic weight (W0.75) per d from casein for 2 weeks and then either 50 (L), 500 (M) or 1500 (H) mg N/kgW0.75per d for 6 weeks. Volatile fatty acids were infused at 500 kJ/kgW0.75per d. Daily WBPNT was measured by continuous intravenous infusion of [l-13C]leucine 3 d before, and on days 2, 21 and 42 after the alteration in protein intake. Whole-body protein-N synthesis (WBPNS) was calculated as the difference between WBPNT and the protein-N losses as urinary NH3and urea. Whole-body protein-N degradation (WBPNS) was then estimated from WBPNS minus protein gain determined from N balance. Fractional rates of WBPNS and WBPND were calculated against fleece-free body N content. WBPNS rates at the L, M and H intakes were respectively 35·1, 41·5 amd 6·37 g/d (P< 0.001) on average over the 6 weeks and WBPND rates were 39·5, 41·1 and 56·8 g/d (P< 0.001). The fractional rates of WBPNS were 5·01, 6·37 and 7·73% per d (P< 0.001) while those of WBPND were 5·64, 6·29 and 6·81% per d (P< 0.005) respectively. On days 2, 21 and 42, WBPNS rates at intake H were 54·0, 61·8 and 75·4 g/d (P= 0·03) respectively, and WBPND rates were 43·2, 56·4 and 70·9 g/d (P= 0.03); at intake L the amounts were 38·2, 34·2 and 32·8 g/d for WBPNS (P= 0.003) and for WBPND were 43·4, 38·0 and 36·9 g/d (P= 0·016) respectively. There were no significant (P> 0·05) differences in fractional rates of WBPNS and WBPND with time at either the L or H intake. We concluded that absolute protein turnover was affected both by dietary protein intake and by body condition while the fractional rate of turnover was predominantly influenced by intake. |
| Databáze: | OpenAIRE |
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