The mechanisms involved in onset of allergic manifestations in the nose.

: The purpose of this study has been to evaluate the degree of participation of the direct and indirect effects of histamine on nasal vasculature and nasal glands in causing clinical manifestations of nasal allergy. Vidian neurectomy, which cuts almost all of the parasympathetic nerve supply and the major portion of the sympathetic supply to the nasal mucosa, apparently almost completely abolished nasal hypersecretion induced by antigen and by topical application of 20 micrograms or 100 micrograms of histamine. However, a maximum dose of histamine (5 mg) induced 0.32 +/- 0.14 ml/10 min of nasal secretion from vidian neurectomized nasal mucosa. Albumin values of nasal secretion induced by topical histamine (2 mg) were significantly higher than those induced by acetylcholine (20 mg). This shows that histamine, depending upon the quantity present in the nasal mucosa, causes various degrees of transudation of plasma by its direct effect on nasal vasculature, in contrast to the fairly direct glandular effect of acetylcholine. However, the content of total histamine in allergic nasal mucosa was 7.1 +/- 3.5 micrograms/g which does not differ from normal controls. Judging from these data, nasal secretion which could be induced by the direct effect of chemical mediators on the effector cells without involvement of cholinergic reflex excitation was assumed to be minimal.