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The transamination of glutamate and aspartate during absorption in vitro by small intestine of chicken, guinea‐pig and rat
Author(s) -
Parsons D. S.,
VolmanMitchell Hetty
Publication year - 1974
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.1974.sp010589
Subject(s) - transamination , alanine , ileum , jejunum , guinea pig , amino acid , small intestine , biology , biochemistry , in vivo , in vitro , medicine , endocrinology , microbiology and biotechnology
1. Procedures are described for direct measurement of the extent and rate of transamination of glutamate and aspartate over periods of up to 90 min, during absorption in vitro by the small intestine of chicken, guinea‐pig, and rat. 2. During absorption of dicarboxylic amino acids by rat small intestinal segments circulated through the lumen in vitro , alanine contributed up to 85% of the amino acids appearing in the fluid secreted at the serosal surface. In guinea‐pig and chicken intestine, the proportion of alanine in the secreted amino acids did not exceed 60%. 3. For the different species studied, a relationship was found between the extent to which the dicarboxylic amino acids were transaminated to alanine and the total amount of GPT found in other studies to be present in the intestinal mucosa. In both rat and guinea‐pig small intestine, the proportion of alanine in the total amino acids appearing at the serosal surface was similar in the jejunum and ileum. The rate of appearance of alanine in serosal fluid was greater in the ileum than in the jejunum of the rat. 4. Reasons are given for supposing that for all the species studied there is a limit to the capacity of the small intestinal mucosa to subject free dicarboxylic amino acids to transamination. It is concluded, however, that it is unlikely that this capacity will be exceeded under in vivo conditions.