Pharmacological characterization of receptors on blood vessels in the tympanic membrane involved in otitis media.

ABSTRACT

Acetylcholine dropped onto the meatal surface of the tympanic membrane evoked vasodilatation and a vascular leakage to the middle ear cavity. The vasoreactions were atropine-resistant. Substance P and vasoactive intestinal polypeptide (VIP) injected intravenously caused a marked vascular leakage and VIP also vasodilatation. These blood vessel changes seem to be regulated by the parasympathetic nerves as they were inhibited by vagotomy. Constriction of the tympanic membrane vessels was mediated through alpha-receptors.