Effect of Epinephrin on Normal and Diabetic Response to Insulin

Abstract

The search for a cause of the marked difference in the course of action of insulin intravenously injected in the normal and depancreatized dog 1 brings up the question whether epinephrin secretion in response to low blood sugar can be responsible for the rapid return to the initial level which sets in at 20 to 25 minutes in the normal animal.

When the action of 3 mg. of epinephrin (3 cc. of 1:1000 solution) is superimposed on insulin action in normal and diabetic dogs they still show respectively a curve with a definite minimum at 20 minutes and a continuous drop to at least 60 minutes. Eight experiments were carried out to cover a reasonable dose range of both drugs. An example is given in Table I.

According to the data of Hrubetz 2 the amount of epinephrin given should be more than enough to counteract the insulin effect if the 2 drugs were direct antagonists. Control experiments where epinephrin alone is given, as well as the late blood sugar rise when both drugs are given, indicate also that the epinephrin dose is large enough to meet the requirements of the experiment, i. e., give a blood sugar raising effect equal to the blood sugar lowering effect of the insulin. Against a background of several hundred blood sugar curves we would judge that with the doses here used the epinephrin has little effect on the course of insulin action and asserts itself only after the action of the latter has passed off.

The lack of rapid return of blood sugar towards the initial level in the diabetic animal cannot be attributed to absence of mobilizable liver glycogen. Epinephrin alone causes the usual mobilization of sugar in the diabetic dog.