Plasma extravasation through neuronal stimulation in human nasal mucosa in the setting of allergic rhinitis

We have previously shown that capsaicin nasal challenge in subjects with allergic rhinitis produces a dose-dependent increase in the albumin content of nasal lavage fluids. In the present set of studies, we determined whether this observation represents plasma extravasation that is neuronally mediated. To evaluate whether glandular secretions contribute to the albumin increase in nasal lavage fluids, volunteers with allergic rhinitis were pretreated with atropine or placebo before capsaicin challenge. Atropine significantly reduced the volume of returned lavage fluids and their lysozyme content but increased their albumin and fibrinogen content. To assess the contribution of sensory nerve stimulation, subjects with allergic rhinitis were pretreated in a second study with lidocaine or placebo before capsaicin challenge. Lidocaine significantly attenuated the capsaicin-induced increases in the volume of nasal lavage fluids, as well as their lysozyme and albumin content. To rule out the possibility of a direct effect of lidocaine on blood vessels rather than on nerves, healthy subjects were pretreated in a third study with lidocaine or placebo before bradykinin nasal challenge. Lidocaine did not affect the bradykinin-induced increase in the albumin content of nasal fluids. We conclude that, in allergic rhinitis, high-dose capsaicin induces plasma extravasation in the human nose and that this effect is neuronally mediated. This provides more definitive evidence that neurogenic inflammation can occur in vivo in the human upper airway.