Portal-drained viscera and hepatic fluxes of branched-chain amino acids do not account for differences in circulating branched-chain amino acids in rats fed arginine-deficient diets
Tóm tắt
Concentrations and fluxes of amino acids across the portal-drained viscera (PDV) and liver were assessed in rats fed a meal of one of three arginine-deficient diets containing either alanine or the arginine precursors, ornithine or citrulline. A previous report included findings of seven arginine-related amino acids and indicated that only the citrulline-containing diet protected blood arginine concentrations. In the present report we extend these findings and note that the concentrations and fluxes of the non-arginine-related amino acids showed remarkable consistency across diet groups. However, total branched-chain amino acid (BCAA) concentrations of arterial blood were higher in rats fed the - Arg/+ Ala and the - Arg/+ Orn diets than in rats fed the control (+ Arg) diet. The elevated BCAA correlated with higher circulating concentrations of other essential amino acids but were inversely correlated with arginine concentrations. PDV and hepatic fluxes of BCAA were not different across diet groups, indicating that amino acid absorption and hepatic utilization of BCAA were generally comparable across diet groups. Hepatic concentrations of 14 of 22 measured amino acids, including total BCAA, were correlated with their arterial concentrations. The circulating concentrations and net PDV and hepatic fluxes of rats fed the control diet were comparable to our previous observations in fed rats and illustrate the role of the liver in utilization of diet-derived essential amino acids.
Tài liệu tham khảo
Block KP, Aftring RP, Buse MG (1990) Regulation of rat liver branched-chain alphaketo acid dehydrogenase activity by meal frequency and dietary protein. J Nutr 120: 793–799
Block KP, Aftring RP, Mehard WB, Buse MG (1987) Modulation of rat skeletal muscle branched-chain alpha-keto dehydrogenase in vivo: effects of dietary protein and meal consumption. J Clin Invest 79: 1349–1358
Block KP, Heywood BW, Buse MG, Harper AE (1985) Activation of rat liver branchedchain 2-oxo acid dehydrogenasein vivo by glucagon and adrenaline. Biochem J 232: 593–597
Brosnan JT, Man K-C, Hall DE, Colbourne SA, Brosnan ME (1983) Interorgan metabolism of amino acids in streptozotocin-diabetic ketoacidotic rats. Am J Physiol 244: E151-E158
Castillo L, Ajami A, Branch S, Chapman TE, Yu Y-M, Burke JF, Young VR (1994) Plasma arginine kinetics in adult man: response to an arginine-free diet. Metabolism 43: 114–122
Crowell PL, Block KP, Repa JJ, Torres N, Nawabi MD, Buse MG, Harper AE (1990) High branched-chain alpha-keto acid intake, branched-chain alpha-keto acid dehydrogenase activity, and plasma and brain amino acid and plasma keto acid concentrations in rats. Am J Clin Nutr 52: 313–319
Demigné C, Rémésy C, Fafournoux P (1986) Respective contribution of plasma branched-chain amino acids and 2-keto acids to the hepatic metabolism of the carbon moiety of branched-chain amino acids in fed rats. J Nutr 116: 2201–2208
Elia M (1991) The inter-organ flux of substrates in fed and fasted man, as indicated by arterio-venous balance studies. Nutr Res Rev 4: 3–31
Eriksson T, Wiesel K, Voog L, Hagman M (1989) Diurnal rhythms in rat plasma amino acids. Life Sciences 45: 980–986
Fafournoux P, Remesy C, Demigne C (1990) Fluxes and membrane transport of amino acids in rat liver under different protein diets. Am J Physiol 259: E614-E625
Fernstrom JD, Fernstrom MH, Grubb PE (1987) Twenty-four hour variations in rat blood and brain levels of the aromatic and branched-chain amino acids: chronic effects of dietary protein content. Metabolism 32: 643–650
Goldberg AL, Chang TW (1978) Regulation and significance of amino acid metabolism in skeletal muscle. Fed Proc 37: 2301–2307
Gross KL, Hartman WJ, Ronnenberg A, Prior RL (1991) Arginine-deficient diets alter plasma and tissue amino acids in young and aged rats. J Nutr 121: 1591–1599
Hara Y, May RC, Kelly RA, Mitch WE (1987) Acidosis, not azotemia stimulates branched-chain amino acid catabolism in uremic rats. Kidney Int 32: 808–814
Harper AE (1983) Dispensible and indispensible amino acid interrelationships. In: Blackburn GL, Young VR, Grant JP (eds) Amino acids: metabolism and medical applications. John Wright, PSG, Inc, Littleton, MA, pp 105–121
Harris RA, Paxton R, Goodwin GW, Kuntz MJ, Shimomura Y, Han A (1986) Regulation of branched-chain amino acid metabolism. Biochem Soc Trans 14: 1005–1008
Hartman WJ, Prior RL (1992) Dietary arginine deficiency alters flux of glutamine and urea cycle intermediates across the portal-drained viscera and liver of rats. J Nutr 122: 1472–1482
Hartman WJ, Torre PM, Prior RL (1994) Dietary citrulline but not ornithine counteracts dietary arginine deficiency in rats by increased splanchnic release of citrulline. J Nutr 124:1950–1960
Hutson SM, Harper AE (1981) Blood and tissue branched chain amino acid and a-keto acid concentrations: effect of diet, starvation, and disease. Am J Clin Nutr 34: 173–183
Milner JA, Visek WJ (1978) Dietary protein intake and arginine requirements in the rat. J Nutr 108:382–391
Moundras C, Berdcovici D, Remesy C, Demigne C (1992) Influence of glucogenic amino acids on the hepatic metabolism of threonine. Biochim Biophys Acta 1115: 212–219
Prior RL (1993) Time after feeding and dietary arginine deficiency alter splanchnic and hepatic amino acid flux in rats. J Nutr 123: 1538–1553
SAS (1988) SAS/STAT User's Guide Release 603, Statistical Analysis Systems Institute, Inc, Cary, NC
Soemitro S, Block KP, Crowell PL, Harper AE (1989) Activities of branched-chain amino acid-degrading enzymes in liver from rats fed different dietary levels of protein. J Nutr 119: 1203–1212
Uhe AM, Collier GR, O'Dea K (1992) A comparison of the effects of beef, chicken and fish protein on satiety and amino acid profiles in lean male subjects. J Nutr 122: 467–472
Yamamoto H, Aikawa T, Matsutaka H, Okuda T, Ishikawa E (1974) Interorganal relationship of amino acid metabolism in fed rats. Am J Physiol 226: 1428–1433
Zapalowski C, Hutson SM, Harper AE (1981) Effects of starvation and diabetes on leucine and valine metabolism in the perfused rat hindquarter. In: Walser M, Williamson JR (eds) Metabolism and clinical implications of branched chain amino and ketoacids. Elsevier/North Holland, New York, pp 239–244