Inhibition of compound 48/80-induced intradental sensory nerve activity by disodium cromoglycate and serotonin antagonists.

Local application of compound 48/80 induced long lasting nerve activity in intradental sensory nerves in the teeth of cats and dogs. This effect was inhibited by pretreatment with disodium cromoglycate (DSCG) given locally (2 X 10(-2) M) or i.a. (20 mg/min). DSCG did not have any effect on the nerve excitability per se, as judged from the responses to hypertonic NaCl and air blasta applied to exposed dentin before and after administration of DSCG. Local treatment with lysergic acid diethylamide (0.1--1 mg/ml) and methysergide (0.05--0.5 mg/ml) selectively reduced or inhibited the compound 48/80 induced nerve activity. Systemic administration of methysergide (12.5 microgram/kg) prevented the excitatory effects of compound 48/80 but was without effect when administrated during a state of established activity. The present findings support the hypothesis that compound 48/80 has an indirect effect on intradental sensory nerves and indicate that vascular reactions take part in intradental sensory nerve excitation.