| Abstract: | Plasma and urinary amino acid concentrations were determined from a cross-sectional sample of dogs of all ages. Reference or base line values for these components were established for five different age groups. A general decrease in urinary excretion of amino acids for each gram of creatinine was found during the developmental period. This decrease was not correlated to changes in plasma concentrations, which varied for the individual amino acids. The decrease did appear to be related to the functional maturation of the kidney. Several methylated basic amino acids were identified in the urine. Of these, NG, NG- and NG,N'G-dimethylarginine, and trimethyllysine had not been previously reported as constituents of dig urine, but are major components of the urinary amino acids, expecially in newborn animals. The 3-methylhistidine is also excreted in large amounts by dogs and measurable quantities of this compound appear in the plasma. These findings suggest an active metabolic function for methylated amino acids in the dog. |
