Studies on the action of insulin neutralized with alkaline solutions.

It was observed that the result of insulin injections varied with the route of administration. Using normal rabbits for our experiments, it was determined that if the injection was given intradermally the effect was more lasting than if an equal amount had been injected subcutaneously. These findings, the subject of an earlier paper, led to the question as to whether or not similar results can be obtained in the human body. Before proceeding with our studies it was found necessary to conduct comprehensive preliminary tests in animals, the results of which were important biologically and clinically. The following problems presented themselves:

(1) What pathologic changes does the intradermal injection of insulin cause in the skin?

(2) Are the changes following the intradermal injection of neutralized insulin of a different character?

(3) Is neutralized insulin less effective than the original preparation?

The tests which were to form the basis for the answer to the first two questions were made with intradermal and subcutaneous injections into normal rabbits and rats of the original preparation (iletin). The readings made at the end of 1/2, 1, and 1 1/2 hour periods coincide with the observations of D. J. Bowie and W. L. Robinson. 1