ABSTRACT
Skin blood flow is regulated by different types of mechanisms. This multiple regulation makes it possible that in some regions blood flow can be increased by up to a 1000-fold from the minimal value. In connection with the regulation of body temperature or circulation, a change in skin blood flow can occur simultaneously in nearly all skin regions. The participation of endogenous opioids in cutaneous vasoconstriction in man was suggested by the observation that i.v. injection of naloxone can produce a rise in blood flow and skin temperature in the fingers and the hand. The cutaneous reactive hyperemia, which can be observed after occlusion of blood vessels, is absent after capsaicin pretreatment. The normal response to an intracutaneous injection of histamine into the human forearm is formation of a wheal surrounded by a flare due to neurogenic vasodilatation. Vasodilatation in the skin is under the influence of several mechanisms which can be divided into neuronal mechanisms and local mechanisms.
