A technique used for study of permeability and vasodilation in the middle ear was adapted to study the response of nasal mucosa [dog] to common inflammatory mediators involved in the natural production of allergic or infectious rhinitis. All of the mediators tested (histamine, prostaglandin E1, bradykinin, the C3a fraction of complement, Escherichia coli endotoxin and lysozyme) increased nasal permeability to the isotopic tracer 99mTc as the pertechnetate ion. Histamine increased the permeability of nasal mucosa to Te-labeled plasma protein. The nasal mucosa is approximately 10 times as permeable to the pertechnetate ion as middle ear mucosa. Nasal mucosa was also permeable to protein, even in the absence of inflammatory mediator, in contrast to prior studies of middle ear mucosa that showed little or no permeability in the absence of inflammatory mediator. In almost all cases, a corresponding change in vasodilation accompanied permeability changes.
