Plasma arginine kinetics in adult man: response to an arginine-free diet.
To explore the response of whole-body arginine metabolism to a change in arginine intake, plasma arginine kinetics were investigated in eight healthy adult men who received an L-amino acid diet supplying an Arg-rich or Arg-free intake for 6 days before undergoing a tracer study on day 7. The tracer protocol lasted for 8 hours. For the first 3 hours subjects remained in the postabsorptive (fasted) state, and during the following 5 hours they consumed small meals at 30-minute intervals. Primed continuous intravenous infusions of L-[guanidino-13C]arginine, L-[5,5,5-2H3]leucine, and [15N2]urea were administered to estimate plasma amino acid fluxes and the rate of urea production. For the fasted and fed states, plasma arginine fluxes (mumol.kg-1.h-1, mean +/- SD) were 69 +/- 8 and 87 +/- 12 (P < .01), respectively, for the Arg-rich diet and 63 +/- 14 and 51 +/- 7 (P < .01, from Arg-rich) for the Arg-free diet. Compared with the Arg-rich results, fed-state plasma arginine and ornithine concentrations were decreased (P < .01) and citrulline concentration was increased (P < .01) during the Arg-free diet period. Leucine fluxes and rates of urea production did not differ between the diet groups. The lower fed-state arginine flux in subjects receiving the Arg-free compared with the Arg-rich diet appears to be entirely due to the decreased rate of entry of arginine from the intestine in the former group.(ABSTRACT TRUNCATED AT 250 WORDS)
Castillo
L
L
Laboratory of Human Nutrition and the Clinical Research Center, Massachusetts Institute of Technology, Cambridge 02149.
Ajami
A
A
Branch
S
S
Chapman
T E
TE
Yu
Y M
YM
Burke
J F
JF
Young
V R
VR
D000328:Adult; D001120:Arginine / Q000008:administration & dosage / Q000097:blood* / Q000378:metabolism; D002247:Carbon Isotopes; D002851:Chromatography, High Pressure Liquid; D002956:Citrulline / Q000097:blood; D003903:Deuterium; D005215:Fasting / Q000502:physiology; D005526:Food, Formulated; D006801:Humans; D007262:Infusions, Intravenous; D007651:Keto Acids / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism; D007930:Leucine / Q000008:administration & dosage / Q000097:blood / Q000378:metabolism; D008297:Male; D009587:Nitrogen Isotopes; D009952:Ornithine / Q000097:blood; D013997:Time Factors; D014508:Urea / Q000008:administration & dosage / Q000378:metabolism / Q000652:urine
D002247:Carbon Isotopes; D007651:Keto Acids; D009587:Nitrogen Isotopes; D002956:Citrulline; C013082:alpha-ketoisocaproic acid; D014508:Urea; D001120:Arginine; D003903:Deuterium; D009952:Ornithine; D007930:Leucine