NEUROPHYSIOLOGY OF MAST CELL-NERVE INTERACTIONS IN THE AIRWAYS

The sensitized guinea pig was employed as a model to study the effect of immunological activation of resident mast cells on neuronal activit y in the airways. The trachea was isolated with the vagus nerves and v agal sensory ganglia intact. Using conventional electrophysiological r ecording techniques, we noted that antigenic stimulation led to an inc rease in the sensitivity of sensory nerve endings located in the airwa y wall. Moreover, previous work has revealed that antigen challenge po tentiates action-potential-driven tachykinin release from afferent fib ers in the guinea pig isolated airway. Anatomical and electrophysiolog ical studies indicate that tachykinin-containing sensory fibers direct ly innervate the local parasympathetic ganglion neurons in the airway. Therefore, antigen-induced increases in the excitability of sensory f ibers in the airways can increase parasympathetic tone in the airway b y increasing central and peripheral reflex arcs. In addition, we have found that antigen stimulation has direct effects on the excitability of the parasympathetic ganglion neurons. Considered together, the data demonstrate that increased vagal sensory and parasympathetic activity may be a consequence of the allergic reaction in the airways.