Neurogenic inflammation in the skin of the rabbit.

A flare-like spread of vasodilatation can be demonstrated in the limb skin of the anaesthetised rabbit using laser doppler flowmetry. Spread of dilatation from a small mechanical injury (nicking the skin) extends 5-10 mm. The size and time course of the dilatation are as expected from the low frequency C-nociceptor firing that occurs in response to similar nearby injury. Since C-nociceptors cause significant vasodilator responses at frequencies less than 1 Hz, it is proposed that they may often have a pro-inflammatory action without producing any reflex or sensory effects.