Extraction of amino acids from and their addition to renal blood plasma

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Abstract
Twenty paired samples of arterial and renal venous plasma, collected simultaneously from dogs in ammonium chloride acidosis, were analyzed by column chromatography for 23 α-amino acids. Fifteen additional paired samples from dogs in acute metabolic alkalosis were similarly analyzed. In ammonium chloride acidosis, glutamine plus asparagine, glycine, citrulline, tryptophan, and proline are extracted from renal blood plasma. Alanine, serine, glutamic acid, cystine, and ornithine are added to renal venous plasma. The addition of glutamic and aspartic acids amounts only to 4% of the extraction of glutamine plus asparagine. It is, therefore, probable that both α-amino and amide nitrogens are removed from the parent amide molecules. In acute metabolic alkalosis, the extraction of glutamine plus asparagine is halved, on an average. The extraction of glycine and the addition of alanine and serine are essentially unchanged. Therefore, only the extraction of glutamine plus asparagine varies to a quantitatively significant degree with changes in acid-base balance which markedly alter the rate of excretion of ammonia.