The supposed relation of the adrenals to reflex volume changes in the denervated limb

Abstract

Bayliss 1 showed that when the central end of a peripheral nerve (sciatic) is stimulated the volume of a hind limb (denervated by section of the anterior crural and sciatic nerves) increases coincidently with the rise of blood pressure and then diminishes to less than the initial volume. He explained the dilatation of the limb as a passive dilatation due to the increase of blood pressure and the subsequent constriction as a local reaction, “the muscular coat of the arteries reacting, like smooth muscle in other situations, to a stretching force by contraction.”

Von Anrep 2 stated that constriction of the limb never occurred in the absence of the adrenals. He drew the conclusion that it is due to a reflex increase in the epinephrin output, and that the explanation of Bayliss was not satisfactory.

We have reinvestigated the question in a series of about 50 animals, chiefly dogs.

We find that a typical reaction can be elicited in acute experiments after the adrenals have been clipped or tied or the glands excised, in the great majority of dogs in which before interference with the adrenals the reaction was present. In a certain number of animals, the reaction has not been obtained by us either before or after interference with the adrenals. Bayliss 3 seems also to have encountered animals in which similar reactions were not obtainable.

A considerable number of experiments were made on dogs which had recovered from adrenal operations entailing marked interference with, or suppression of the epinephrin output (removal of one adrenal and the greater part of the other, with curetting away of the remaining medulla and denervation of the fragment). Even after removal of the adrenal remnant typical reactions were obtained.