Passage of Insulin through the Wall of the Gastro-intestinal Tract of the Infant Rat

Abstract

IT is well known that protein molecules can pass through the wall of the gastro-intestinal tract into the blood in new-born animals¹. The possibility, therefore, exists that hormones which might be present in milk also are absorbed by infant animals. To test this hypothesis, insulin, which is ineffective when given per os to adult animals, was administered to infant rats by a stomach tube. Regular insulin was used in a dose of 40 units/ml.; 1 ml./100 gm. body-weight. Rats were starved for 16–18 hours at 30° C. environmental temperature before the start of the experiment. Control animals received an equivalent dose of saline. All rats were killed two hours after insulin administration and blood glucose levels were determined by a modification of the Somogyi–Nelson method².