[Current aspects of nasal hyperreactivity].

The term hyper-reactivity defines an inadequate reaction of the nose to normal airborne stimuli that are harmless to most of the population. In such cases the nose always shows exactly the same symptoms, irrespective of whether the rhinitis is allergic (IgE- or cell-mediated) or nonspecific (vasomotor). These symptoms include sneezing, nasal obstruction, hypersecretion, and itching of the nose. The vascular supply of the nose consists of capacitance vessels (veins, venules, sinusoids), resistance vessels (arteries, arterioles), and exchange vessels (capillaries of fenestrated types). Drug and mediator effects may be directed to different nasal vessel systems. The autonomic innervation of the nose is complex. Some neuropeptides have been demonstrated, in addition to the classical neurotransmitters of the sympathetic and parasympathetic system. Neuropeptide Y (NPY) is found in adrenergic fibers, vasoactive intestinal peptide (VIP) in cholinergic neurones; substance P (SP), calcitonin-gene-related peptide (CGRP) and neurokinine (NKA) are found in sensory nerves. The possible significance of the different neurotransmitters and mediators in nasal hyperreactivity is discussed.