Daily delivery of dietary nitrogen to the periphery is stable in rats adapted to increased protein intake.
Dietary nitrogen was traced in rats adapted to a 50% protein diet and given a meal containing 1.50 g (15)N-labeled protein (HP-50 group). This group was compared with rats usually consuming a 14% protein diet and fed a meal containing either 0.42 g (AP-14 group) or 1.50 g (AP-50 group) of (15)N-labeled protein. In the HP group, the muscle nonprotein nitrogen pool was doubled when compared with the AP group. The main adaptation was the enhancement of dietary nitrogen transferred to urea (2.2 +/- 0.5 vs. 1.3 +/- 0.1 mmol N/100 g body wt in the HP-50 and AP-50 groups, respectively). All amino acids reaching the periphery except arginine and the branched-chain amino acids were depressed. Consequently, dietary nitrogen incorporation into muscle protein was paradoxically reduced in the HP-50 group, whereas more dietary nitrogen was accumulated in the free nitrogen pool. These results underline the important role played by splanchnic catabolism in adaptation to a high-protein diet, in contrast to muscle tissue. Digestive kinetics and splanchnic anabolism participate to a lesser extent in the regulation processes.
Morens
C
C
Institut National de la Recherche Agronomique, Unité de Physiologie de la Nutrition et du Comportement Alimentaire, Institut National Agronomique de Paris-Grignon, F-75005 Paris, France.
Gaudichon
C
C
Fromentin
G
G
Marsset-Baglieri
A
A
Bensaïd
A
A
Larue-Achagiotis
C
C
Luengo
C
C
Tomé
D
D
D000222:Adaptation, Physiological; D000596:Amino Acids / Q000097:blood; D000818:Animals; D001798:Blood Proteins / Q000378:metabolism; D004044:Dietary Proteins / Q000378:metabolism*; D002149:Energy Intake; D005215:Fasting; D005746:Gastric Emptying; D007413:Intestinal Mucosa / Q000378:metabolism; D007668:Kidney / Q000378:metabolism; D008297:Male; D008894:Milk Proteins; D008954:Models, Biological; D018482:Muscle, Skeletal / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D009587:Nitrogen Isotopes; D009929:Organ Size; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D014508:Urea / Q000097:blood / Q000652:urine; D015430:Weight Gain
D000596:Amino Acids; D001798:Blood Proteins; D004044:Dietary Proteins; D008894:Milk Proteins; D009587:Nitrogen Isotopes; D014508:Urea; D009584:Nitrogen