Antigen depolarizes guinea pig bronchial parasympathetic ganglion neurons by activation of histamine h-1 receptors.. Myers, Allen C., and Bradley J. Undem. Johns Hopkins Asthma and Allergy Center, 5501 Hopkins Bayview Blvd., 3A62, Baltimore, MD 21224
APStracts 2:0004L, 1995.
Studies were carried out to evaluate the mechanism by which neurotransmission through airway parasympathetic ganglia may be modulated during immediate hypersensitivity reactions. Guinea-pigs were passively sensitized by injection of guinea pig serum containing high-titer anti-ovalbumin antibodies. Intracellular recordings were obtained from intrinsic parasympathetic ganglion neurons from the right main-stem bronchus in vitro. Ovalbumin (10 ug/ml) elicited a membrane potential depolarization and changes in membrane resistance in bronchial ganglion neurons from passively sensitized guinea-pigs. Histamine mimicked the depolarizing effect of ovalbumin in a concentration-dependent manner (0.1 - 10 uM) and caused a transient increase and decrease in membrane resistance. Pyrilamine, a histamine H-1 receptor antagonist, inhibited the histamine-induced membrane depolarization and decrease in resistance. By contrast, block histamine H-2 and H-3 receptors did not inhibit histamine-induced depolarization. Pyrilamine also reduced the antigen-induced depolarization of ganglion neurons demonstrating a role for histamine H-1 receptors in this response. The date provide evidence that the antigen-induced depolarization of airway ganglion neurons is secondary to an antigen-antibody interaction on intrinsic mast cells and the consequential effect of histamine on H-1 receptors. These studies demonstrate that histamine released during an immediate hypersensitivity reaction has direct effects on airway parasympathetic nerves. 

Received 12 August 1994; accepted in final form 12 January 1995.
APS Manuscript Number L0232-4.
Article publication pending Am. J. Physiol. (Lung Cell. Mol. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 24 February 1995.