Involvement of sensory nerves in hemodynamic reactions.
Small diameter afferent nerves in the pulp contain vasoactive peptides (tachykinins and CGRP) which are released upon nerve stimulation causing long lasting vasodilation. The aim of the present experiments was to study the contribution of afferent nerves in vasodilator reactions in the cat dental pulp when clinical procedures were applied. For this purpose the inferior alveolar nerve (IAN) was cut unilaterally 10 days prior to study. Lower canines were then subjected to various stimuli and blood flow responses in the pulp were monitored by laser Doppler flowmetry. Bipolar electrical tooth stimulation (5 impulses, at 2 Hz, 50 microA) and application of capsaicin (10(-4) M) in a deep cavity instantaneously induced long lasting increases in pulpal blood flow in control teeth but not in denervated teeth. Bradykinin (10(-3) M) applied locally produced a more rapid and larger pulpal vasodilation in innervated than in denervated teeth. Intermittent grinding (3 times, 1 sec each) of surface dentin with a round diamond bur instantly increased flow in control teeth by 53%, whereas in denervated teeth the response was delayed and significantly smaller (16% increase). Deeper preparations produced long lasting responses of similar magnitude on both sides but the onset was much slower in denervated teeth. Percussion and low intensity ultrasonic stimulation (1 sec) instantly caused increased flow in control teeth but not in denervated teeth. The effect was abolished by local anesthetic (mepivacaine) injection apically. Sympathectomy and acute IAN denervation did not alter the responses. The results show that afferent (sensory) nerves contribute importantly to hemodynamic reactions in the pulp in response to clinical procedures.
Olgart
L M
LM
Department of Pharmacology, Karolinska Insitutet, Sweden.
D000818:Animals; D002415:Cats; D003782:Dental Pulp / Q000098:blood supply* / Q000294:innervation*; D006439:Hemodynamics; D009475:Neurons, Afferent / Q000502:physiology*; D012039:Regional Blood Flow / Q000502:physiology; D014664:Vasodilation / Q000502:physiology