TEMPORAL CHANGES IN CONCENTRATIONS OF AMINO-ACIDS IN PLASMA AND WHOLE-BLOOD OF HEALTHY NEONATAL FOALS FROM BIRTH TO 2 DAYS OF AGE

Temporal changes, as well as differences in distribution, in concentra tions of 24 amino acids in plasma and whole blood of neonatal foals we re determined from birth to 2 days of age. In addition, differences in concentrations of amino acids in plasma between mare and foal pairs w ere determined at birth. Significant (P < 0.05) hypoaminoacidemia exis ted for 15 amino acids in plasma of foals at birth, compared with mare s (paired t-test). Concentrations of 7 amino acids (aspartate, glutama te, glutamine, glycine, hydroxyproline, phenylalanine, proline) in pla sma of foals were higher (P < 0.05) at birth than in mares, and concen trations of 2 (taurine, tryptophan) were not different (P > 0.05). Sig nificant (P < 0.05) temporal changes for concentrations of 19 of 24 am ino acids in plasma were observed during the 48-hour period. Concentra tions of 13 of the 19 amino acids in plasma that had significant chang es were higher (P < 0.05) at 48 hours. Significant (P > 0.05) effect o f time on concentration of 5 amino acids (alanine, methionine, phenyla lanine, taurine, threonine) in plasma was not found after birth. Tempo ral changes in concentrations of 7 amino acids (alanine, asparagine, g lutamine, histidine, hydroxyproline, methionine, and threonine) in who le blood were not significantly (P > 0.05) different from those in pla sma. Temporal changes for concentrations of the remaining 17 amino aci ds in whole blood were significantly (P < 0.05) different, compared wi th plasma. Distribution of the concentrations of 18 amino acids betwee n whole blood and plasma was significantly (P < 0.05) different. Conce ntrations of 5 amino acids (citrulline, cystine, glutamine, methionine , tryptophan) were significantly (P < 0.05) lower in whole blood than in plasma, whereas concentrations of 13 amino acids were significantly (P < 0.05) higher in whole blood vs plasma. Concentrations of 6 amino acids (asparagine, isoleucine, leucine, proline, serine, valine) in w hole blood were not significantly different from concentrations in pla sma. Significant differences in temporal patterns of concentrations of amino acids in plasma and whole blood may be attributable to nutritio nal or physiologic changes associated with parturition. Significant di fferences between concentrations of amino acids in whole blood and pla sma may be attributable to ontogeny or specificity of transport system s across cell membranes.