Neurogenic mediators in control of pulpal blood flow.

In view of recent findings, classical nerve-released transmitters that modulate pulpal blood flow share their roles with novel vasoactive peptides. Noradrenaline coexists with neuropeptide Y in sympathetic nerves in the pulp and both substances contribute to a vasoconstriction. Vasoactive intestinal peptide has vasodilator effects and its presence in nerves in the pulp may represent a parasympathetic influence on pulpal vessels. Sensory nerves in the pulp contain a number of peptides which have vasodilatory effects. They are released and cause rapid increase in blood flow when the tooth is reached by an intense stimulus. A population of sensory nerves may thus play a role in instant defense reactions in the pulp.