American Journal of Clinical Nutrition, Vol 65, 984-993, Copyright © 1997 by The American Society for Clinical Nutrition, Inc

ORIGINAL RESEARCH COMMUNICATIONS

Phenylalanine requirements determined by using L-[1-14C]phenylalanine in neonatal piglets receiving total parenteral nutrition supplemented with tyrosine

JD House, PB Pencharz and RO Ball
Department of Animal and Poultry Science, University of Guelph, Canada.

The definition of amino acid requirements for neonates receiving total parenteral nutrition (TPN) is critical for the further improvement of this nutritional regimen. In the present study we investigated the kinetics and requirements of phenylalanine and tyrosine in neonatal piglets receiving TPN. Twenty-four 3-d-old male Yorkshire piglets were fitted with external jugular and femoral catheters and maintained on identical TPN formulations for 5 d. Total amino acid, phenylalanine, tyrosine, and energy intakes were 15, 0.61, and 0.51 g. kg-1 . d-1 and 1.1 MJ . kg-1 . d-1, respectively. On day 5, piglets (three per level) were randomly assigned to receive one of eight phenylalanine intakes: 0.2. 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 1.2 g. kg-1 . d-1. On day 6, phenylalanine kinetics were measured during a 4-h primed, continuous infusion of L-[1-14C]phenylalanine. Plasma phenylalanine and phenylalanine oxidation were statistically similar for the three lowest phenylalanine intakes and increased thereafter. Crossover regression analysis yielded estimates for the mean requirement and safe phenylalanine intake of 0.45 and 0.48 g . kg-1 . d-1, respectively (equivalent to 30 and 32 mg/g amino acids, respectively), in the presence of excess tyrosine. An inability of piglets to maintain a linear oxidative response at phenylalanine intakes > 0.8 g . kg-1 . d-1 (equivalent to 53 mg/g amino acids) was found. These data represent the first direct estimates of phenylalanine requirements in neonates receiving TPN and demonstrate the use of oxidation techniques for the estimation of amino acid requirements during parenteral nutrition.

This article has been cited by other articles:

				P. B. Pencharz, R. Elango, and R. O. Ball An Approach to Defining the Upper Safe Limits of Amino Acid Intake J. Nutr., October 1, 2008; 138(10): 1996S - 2002S. [Abstract] [Full Text] [PDF]

				G. Courtney-Martin, K. P Chapman, A. M Moore, J. H Kim, R. O Ball, and P. B Pencharz Total sulfur amino acid requirement and metabolism in parenterally fed postsurgical human neonates Am. J. Clinical Nutrition, July 1, 2008; 88(1): 115 - 124. [Abstract] [Full Text] [PDF]

				M. Rafii, J. M. McKenzie, S. A. Roberts, G. Steiner, R. O. Ball, and P. B. Pencharz In vivo regulation of phenylalanine hydroxylation to tyrosine, studied using enrichment in apoB-100 Am J Physiol Endocrinol Metab, February 1, 2008; 294(2): E475 - E479. [Abstract] [Full Text] [PDF]

				R. O. Ball, K. L. Urschel, and P. B. Pencharz Nutritional Consequences of Interspecies Differences in Arginine and Lysine Metabolism J. Nutr., June 1, 2007; 137(6): 1626S - 1641S. [Abstract] [Full Text] [PDF]

				K. L. Urschel, C. W. Wilkinson, P. B. Pencharz, and R. O. Ball Coadministration of Ornithine and {alpha}-Ketoglutarate Is No More Effective Than Ornithine Alone As an Arginine Precursor in Piglets Enterally Fed an Arginine-Deficient Diet J. Nutr., January 1, 2007; 137(1): 55 - 62. [Abstract] [Full Text] [PDF]

				A. K. Shoveller, J. A. Brunton, O. Brand, P. B. Pencharz, and R. O. Ball N-Acetylcysteine is a Highly Available Precursor for Cysteine in the Neonatal Piglet Receiving Parenteral Nutrition JPEN J Parenter Enteral Nutr, March 1, 2006; 30(2): 133 - 142. [Abstract] [Full Text] [PDF]

				J. W-C Hsu, L. A Goonewardene, M. Rafii, R. O Ball, and P. B Pencharz Aromatic amino acid requirements in healthy men measured by indicator amino acid oxidation Am. J. Clinical Nutrition, January 1, 2006; 83(1): 82 - 88. [Abstract] [Full Text] [PDF]

				S. Moehn, R. F. P. Bertolo, P. B. Pencharz, and R. O. Ball Development of the Indicator Amino Acid Oxidation Technique to Determine the Availability of Amino Acids from Dietary Protein in Pigs J. Nutr., December 1, 2005; 135(12): 2866 - 2870. [Abstract] [Full Text] [PDF]

				P. B. Darling, M. Dunn, G. S. Gilani, R. O. Ball, and P. B. Pencharz Phenylalanine Kinetics Differ between Formula-Fed and Human Milk-Fed Preterm Infants J. Nutr., October 1, 2004; 134(10): 2540 - 2545. [Abstract] [Full Text] [PDF]

				D. L. Wilkinson, R. F. P. Bertolo, J. A. Brunton, A. K. Shoveller, P. B. Pencharz, and R. O. Ball Arginine synthesis is regulated by dietary arginine intake in the enterally fed neonatal piglet Am J Physiol Endocrinol Metab, September 1, 2004; 287(3): E454 - E462. [Abstract] [Full Text] [PDF]

				P. B. Pencharz and R. O. Ball Amino Acid Needs for Early Growth and Development J. Nutr., June 1, 2004; 134(6): 1566S - 1568S. [Abstract] [Full Text] [PDF]

				R. Sakai, M. Miura, M. Amao, R. Kodama, S. Toue, Y. Noguchi, and T. Kimura Potential Approaches to the Assessment of Amino Acid Adequacy in Rats: A Progress Report J. Nutr., June 1, 2004; 134(6): 1651S - 1655S. [Abstract] [Full Text] [PDF]

				V. E. Baracos Animal Models of Amino Acid Metabolism: A Focus on the Intestine J. Nutr., June 1, 2004; 134(6): 1656S - 1659S. [Abstract] [Full Text] [PDF]

				R. Elango, L. A. Goonewardene, P. B. Pencharz, and R. O. Ball Parenteral and Enteral Routes of Feeding in Neonatal Piglets Require Different Ratios of Branched-Chain Amino Acids J. Nutr., January 1, 2004; 134(1): 72 - 78. [Abstract] [Full Text] [PDF]

				A. K. Shoveller, J. A. Brunton, J. D. House, P. B. Pencharz, and R. O. Ball Dietary Cysteine Reduces the Methionine Requirement by an Equal Proportion in Both Parenterally and Enterally Fed Piglets J. Nutr., December 1, 2003; 133(12): 4215 - 4224. [Abstract] [Full Text] [PDF]

				A. K. Shoveller, J. A. Brunton, P. B. Pencharz, and R. O. Ball The Methionine Requirement Is Lower in Neonatal Piglets Fed Parenterally than in Those Fed Enterally J. Nutr., May 1, 2003; 133(5): 1390 - 1397. [Abstract] [Full Text] [PDF]

				R. F. P. Bertolo, J. A. Brunton, P. B. Pencharz, and R. O. Ball Arginine, ornithine, and proline interconversion is dependent on small intestinal metabolism in neonatal pigs Am J Physiol Endocrinol Metab, May 1, 2003; 284(5): E915 - E922. [Abstract] [Full Text] [PDF]

				G. Courtney-Martin, R. Bross, M. Raffi, J. T. R. Clarke, R. O. Ball, and P. B. Pencharz Phenylalanine requirement in children with classical PKU determined by indicator amino acid oxidation Am J Physiol Endocrinol Metab, December 1, 2002; 283(6): E1249 - E1256. [Abstract] [Full Text] [PDF]

				R. Elango, P. B. Pencharz, and R. O. Ball The Branched-Chain Amino Acid Requirement of Parenterally Fed Neonatal Piglets Is Less than the Enteral Requirement J. Nutr., October 1, 2002; 132(10): 3123 - 3129. [Abstract] [Full Text] [PDF]

				S. A Roberts, J. M Thorpe, R. O Ball, and P. B Pencharz Tyrosine requirement of healthy men receiving a fixed phenylalanine intake determined by using indicator amino acid oxidation Am. J. Clinical Nutrition, February 1, 2001; 73(2): 276 - 282. [Abstract] [Full Text] [PDF]

				R. Bross, R. O. Ball, J. T. R. Clarke, and P. B. Pencharz Tyrosine requirements in children with classical PKU determined by indicator amino acid oxidation Am J Physiol Endocrinol Metab, February 1, 2000; 278(2): E195 - E201. [Abstract] [Full Text] [PDF]

				R. F. P. Bertolo, C. Z. L. Chen, P. B. Pencharz, and R. O. Ball Intestinal Atrophy Has a Greater Impact on Nitrogen Metabolism than Liver By-Pass in Piglets Fed Identical Diets via Gastric, Central Venous or Portal Venous Routes J. Nutr., May 1, 1999; 129(5): 1045 - 1052. [Abstract] [Full Text]

				R. F. P. Bertolo, C. Z. L. Chen, G. Law, P. B. Pencharz, and R. O. Ball Threonine Requirement of Neonatal Piglets Receiving Total Parenteral Nutrition Is Considerably Lower than That of Piglets Receiving an Identical Diet Intragastrically J. Nutr., October 1, 1998; 128(10): 1752 - 1759. [Abstract] [Full Text]