The spinal cord contains multiple factors causing plasma protein extravasation in the skin.

Nervous tissue was analyzed for possible mediators of neurogenic inflammation. Acid extracts of spinal cord or spinal roots contained activity causing plasma protein extravasation when injected into the rat abdominal skin. The activity was more than 1000-fold higher than could be attributed to the content of substance P (SP). It was not depleted from spinal cord after destruction of afferent C fibers by capsaicin and was resistant to proteolytic enzymes. The activity was clearly separated from SP or neurokinins by HPLC or gel filtration and was due to compounds of high polarity and low molecular weight. Further HPLC separated at least 6 peaks, two of which were found to contain adenosine and AMP, respectively, as active substances. The activity of these compounds and of the peaks was reduced by antihistaminics. A further compound identified was 5-HT. Thus, while several active non-peptidergic compounds were found, no clear evidence for a new mediator of neurogenic inflammation was obtained.