Vasodilatation in the dental pulp produced by electrical stimulation of the inferior alveolar nerve in the cat.

The effects of nerve stimulation on blood flow were studied in the dental pulp of anesthetized cats. Changes in iodide disappearance rate (k-value) from dentinal cavities were used to determine changes in pulpal blood flow. Electrical stimulation of the distal end of the cut inferior alveolar nerve after alpha-adrenoceptor blockade (phentolamine, 3 mg/kg) consistently resulted in a rapid increase in disappearance rate. The first stimulation produced the greatest response (an average increase in k-values of 60%) and repeated stimulations showed a successive attenuation in response, the fourth stimulation usually having no effect. A progressive decrease in resting k-values was observed after the first stimulation, indicating an impaired exchange function of the capillary vessels. Systemic pretreatment with propranolol (0.5--1 mg/kg), atropine (3 mg/kg), mepyramine (3 mg/kg) and cimetidine (3 mg/kg) did not influence the rapid increase in k-values produced by the nerve stimulation. The experiments show that vasodilatation in the cat dental pulp produced by stimulation of the inferior alveolar nerve is not mediated by common efferent vasodilatory mechanisms and strengthen the hypothesis that the sensory nerve axon reflex mechanism is involved.