Neurohumoral Features of Afferent Fibers in Man

Introduction Shortly after human skin is injured the area for several centimeters surrounding the site of injury gradually becomes reddened. This flare is a component of the inflammatory response, represents neurogenic vasodilatation,¹⁻³and probably is mediated through the release of one or more Vasodilator substances.⁴⁻⁶The threshold for pain in the flare zone is lowered.⁷ These phenomena have been the topic of a series of investigations in this laboratory⁷⁻¹¹; in this report an attempt is made to define more carefully (a) the nervous pathways implicated and (b) the nature of the mediator substance. Antidromic Vasodilatation after Stimulation of the Distal Portion of Transected Dorsal Roots.—In 1874 Goltz¹²demonstrated that the sciatic nerve contains fibers that induce vasodilatation when stimulated. Shortly thereafter, Stricker¹³concluded that in opposition to the Bell-Magendie law, certain vasodilator fibers apparently leave the spinal cord through the dorsal roots, since