Effect of Administered Glucose upon Amino Nitrogen Content of the Blood. ∗

Abstract

The experiments here recorded arose from investigations into the influence of adrenalin on the amino nitrogen content of the blood. It was recently shown by Davis and Van Winkle 1 that the amino-acid-lowering property of insulin, which we have been studying for some years, is directly due to adrenalin, secreted in response to the administered insulin. Part of the proof is based upon the observation that insulin is without effect on the blood amino acids in adreno-demedullated rabbits. However, the administration of adrenalin induces in these, as well as in normal animals, the characteristic lowering.

Since the response seems to be due specifically to adrenalin, it is possible to infer, under appropriate conditions, that a lowering in blood amino acids is indicative of a discharge of this hormone. We have now made use of this hypothesis to test the response of the adrenal medulla to administered glucose.

To 15 normal students (13 males, 2 females) from 16 to 30 years of age, who volunteered as subjects, glucose was administered after fasting periods of 15 hours. To 4 others, who served as controls, water was given in quantities comparable to those received with the glucose by the experimental subjects. Blood sugar (Folin) and amino nitrogen (Danielson) determinations were made at zero, one, 2 and 4 hours after the first administration of glucose. Glucose was given at zero, one and 2 hours. The results are summarized in Table I.

As a simple explanation of these observations we suggest the following mechanism. Insulin is first secreted in response to the administered glucose. This is indicated by the absence of sustained hyperglycemia,† the evident trend towards hypoglycemia after one or 2 hours, and is in accord with the now abundant evidence of many investigators.