Studies on the action of hormones on the intestinal transport of L-histidine.

Intestinal absorption of L-histidine as affected by insulin, diabetes, hydrocortisone, adrenocorticotrophic hormone (ACTH) and thyroxine has been studied. Intestinal absorption of L-histidine is not significantly increased following insulin administration. Similarly, addition of insulin in vitro did not change the transport activity significantly. When rats are made diabetic on administration of alloxan monohydrate, the transport activity is increased. Hydrocortisone, adrenocorticotrophic hormone and thyroxine treatment increased the absorption of L-histidine by small intestine. However, addition in vitro of ACTH and hydrocortisone did not change the absorption of L-histidines by small intestine. It appears that the facilitative action of these hormones is not due to their direct action of the membrane.