Abstract

The transport of L-tyrosine and 13 derivatives was studied with everted intestinal sacs of golden hamsters. It was found that L-tyrosine, its three monosubstituted derivatives and 3,5-dichloro-L-tyrosine were transported from mucosal to serosal fluids against concentration gradients, while the rest of the disubstituted compounds and N(2,3,5-triiodobenzoyl)-tyrosine did not develop a concentration above the original on either side. Studies with the open-end intestinal segment technique showed that L-tyrosine inhibited the intestinal transport of DCT or MIT and that probenecid, phlorizin or sodium azide had no effect. The inhibitory effect of L-tyrosine was a competitive one.