Alterations in intradental nerve responsiveness induced by electrical stimulation of the inferior alveolar nerve in the cat.
The effects of antidromic nerve stimulation on intradental nerve activity were studied by recording sensory nerve impulses from canine teeth in anaesthetized cats. Nerve responses to application of a solution of hypertonic sodium chloride (0.76 M) in dentinal cavities at various intervals before and after antidromic stimulation of the inferior alveolar nerve were compared. Low-intensity stimulation (2 V, 60 Hz, 0.02 ms) did not affect the nerve responses to subsequent applications of the hypertonic solution. In contrast, high-intensity stimulation (10 V, 10 Hz, 5 ms) induced biphasic changes in the intradental nerve activity, consisting of a transient, increased nerve response to sodium chloride during the first few minutes after stimulation, followed by a period (40 min) of decreased responses. Systemic pretreatment with phentolamine did not influence these effects, whereas after administration of mepyramine and cimetidine the nerve stimulation induced increased responses during a period of 50 min. Local application of substance P in dentinal cavities reduced the nerve responses to subsequent applications of hypertonic sodium chloride, thus mimicking the depressant effect of antidromic stimulation. This inhibitory effect of substance P was abolished by pretreatment with antihistamines. The present results show that electrical stimulation of the inferior alveolar nerve at intensities high enough to excite sensory C fibres alters the responsiveness of intradental nerves. Such changes probably reflect a neurogenic inflammatory-like reaction in the pulp, in which substance P and histamine take part.
D000539:Alveolar Process / Q000294:innervation*; D000818:Animals; D002415:Cats; D002927:Cimetidine / Q000494:pharmacology; D003782:Dental Pulp / Q000294:innervation*; D004558:Electric Stimulation; D010646:Phentolamine / Q000494:pharmacology; D011738:Pyrilamine / Q000494:pharmacology; D012965:Sodium Chloride / Q000494:pharmacology; D013373:Substance P / Q000494:pharmacology; D014276:Trigeminal Nerve / Q000187:drug effects / Q000502:physiology*
D013373:Substance P; D012965:Sodium Chloride; D002927:Cimetidine; D011738:Pyrilamine; D010646:Phentolamine