The effect of glucose on tyrosine transport by the intestine in vitro.

The influence of glucose on intestinal amino acid transport has been reported as inhibitory, stimulating or indifferent by different workers. Because these conflicting reports could be related to solute concentrations as well as the individual amino acid under study, the question was investigated again using varying concentrations of solute. The amino acid tyrosine was chosen for study because most workers on this question have used other neutral amino acids like glycine. Everted sacs of the rat intestine were used. Although it appeared that in low concentration glucose and tyrosine facilitated each other and at higher concentrations this facilitation disappeared. These differences were not statistically significant (P greater than 0.05) when compared to the transport activity observed when these substances were studied alone. It is concluded that glucose and tyrosine do not affect the transport of each other in the rat intestine. These results are discussed and their possible practical value commented on the light of the conflicting observations referred to above which have been obtained with other neutral amino acids.