SYMPATHETIC-NERVE DISTURBANCE AND FINE-STRUCTURE OF ADRENERGIC-NERVE TERMINALS IN NASAL-MUCOSA AFTER EXPERIMENTALLY-INDUCED NASAL HYPERSENSITIVITY

Electron microscopic observations were used to study the relation betw een the adrenergic nerve terminal and the effector cell in the nasal m ucosa of toluene diisocyanate-sensitized and non-sensitized guinea pig s. Adrenergic nerve terminals were abundantly distributed in the adven titia of arterioles, however. no synapse formation was observed in smo oth muscle cells of the mesothelium, i.e., effector cells. Adrenergic nerve terminals were observed separated from smooth muscle cells of th e mesothelium of the arteriol by distances of 1000 angstrom-3000 angst rom. Neurotransmission by the sympathetic nerve in the nasal mucosa is assumed to be by diffusion of norepinephrin (NE) or by diffusive syna ptic conduction. The mechanism of sympathetic hypofunction in the nasa l mucosa in nasal hypersensitivity is assumed to be as follows: Releas ed histamine directly stimulates H-1 receptors at the sympathetic nerv e terminal, leading to the release of NE. Once released, NE is not rea dily reabsorbed, and is gradually depleted in the sympathetic nerve te rminal, leading to hypofunction of the sympathetic nerve.