Autonomic nerves and middle ear fluid production. An experimental study in the rat.

The production of middle ear effusion by mechanical stimulation was studied in sympathectomized and vagotomized animals. Mechanical stimulation was obtained by a 14 degree C airstream in the external auditory canal. In sympathectomized animals this procedure caused effusion production and vasoconstriction of pars flaccida vessels. Mechanical stimulation in the vagotomized animals did not cause any production of effusion material. Degranulated mast cells were observed in all animals, including controls. The study indicates that the vagal nerve, in contrast to the sympathetic nerves, is involved in the mechanisms causing the leakage of fluid into the middle ear cavity, when cold air is blown into the external auditory canal.