Excitation by lyoniol-A of vagal afferent nerves and the reflex autonomic and somatic actions in rats.

Lyoniol-A (2mg/kg, i.v.), a toxic component isolated from the Ericaceous tree, markedly caused the increase in rate of discharges from vagal afferent nerves in the rat. This agent also caused respiratory depression, hypotension and the relief of decerebrate rigidity. These effects of lyoniol-A on the respiration an the rigidity were absent under conditions of bilateral cervical vagotomy, and the hypotension was abolished by sectioning of both vagal and carotid sinus nerves. These results suggest that the excitation by lyoniol-A of the afferent activities reflexly produces respiratory depression, hypotension and the relief of decerebrate rigidity.