THE MECHANISM OF ANTIDROMIC VASODILATATION

Abstract

1. In the skin, in response to stimulation of the posterior root fibres, histamine is released into the venous blood. The release of histamine is paralleled by an increase in blood flow.2. In muscles, antidromic stimulation of the posterior roots does not release histamine nor increase the blood flow.3. After the intravenous injection of antihistamine preparations, dorsal root stimulation causes a much smaller vasodilatation in the skin.4. Antihistamine preparations prevent the skin vasodilatation caused by histamine but not that caused by acetylcholine.5. It is concluded that the antidromic vasodilatation in the skin, produced by dorsal root stimulation, is due to the release of histamine in the skin as first suggested by Lewis and Marvin.