Abstract
There are conflicting reports in the literature concerning the influence of the vagus nerves on insulin secretion. Some reports 1 , 4 support the idea that vagal stimulation increases the pancreatic output of insulin. Other work 5 , 6 , 7 fails to substantiate this point of view.
Even with the marked increase in sensitivity to insulin due to hypophysectomy, Keller 8 was unable to produce hypoglycemia in the dog by faradic stimulation of the distal end of the vagi sectioned in the upper abdomen.
These conflicting reports and the studies of Portis and Zitman 9 who attempt to explain the clinical syndromes of weakness and fatigue in psychoneurotic patients on the basis of a vagal induced hyperinsulinism led us to make the following experiments.
Under sodium pentobarbital anesthesia one or both vagus nerves were isolated in the neck. The right vagus was stimulated alone in some dogs; the right and left vagi were stimulated consecutively in some dogs; and the right and left vagi were stimulated simultaneously in some dogs with the tetanizing faradic current. Stimulation was of sufficient strength to cause a marked slowing of cardiac rate as a criterion of vagal effects. Stimulation was continued from 40 minutes to 5 3/4 hours. Vagal stimulation was continuous except when asystole, cyanosis, apnea, retching or restlessness necessitated either decreasing the current or stopping the stimulation for periods not exceeding 2 minutes in any dog.
Insulin was given subcutaneously to 2 dogs, as indicated in Table I, to be sure that neither the anesthetic nor the vagal stimulation prevented insulin hypoglycemia.
The detailed results are recorded in the table.
Results. When insulin was given subcutaneously to Dog 8 during pentobarbital anesthesia, the usual hypoglycemia resulted. Similarly, when insulin was given subcutaneously to Dog 7 after 3 hours of vagal stimulation, and during continuation of the stimulation, the usual hypoglycemia resulted. This indicates that neither sodium pentobarbital nor vagal stimulation interferes with production of insulin hypoglycemia.
Get full access to this article
View all access options for this article.