The long term goals are to identify the origins and distribution of VIP and SP-containing sensory and motor nerves in the airways. The basic hypothesis is that VIP-and SP-containing nerve fibers that innervate the airways originate from sensory nerve cell bodies located in the nodose, jugular, and dorsal root ganglia and from postganglionic nerve cell bodies located in the intrinsic airway ganglia. The distribution of nerve fibers that originate from sensory ganglia will be determined by injecting wheat germ agglutinin (WGA) into nodose, jugular and dorsal root ganglia. WGA binds at cell membranes of nerve cell bodies and is transported through the axons to nerve terminals in the lung. Once the sensory nerve terminals are identified, the peptide (VIP or SP) content of the same nerve terminal will be determined by colocalization with immunocytochemistry. In some experiments, WGA will be conjugated to gold particles and injected into the ganglia. Airway from these experiments will be used to study the ultrastructural features of specific sensory nerve terminals. The possible occurrence of sensory neurons located in the intrinsic airway ganglia will be determined by soaking distal stumps of transsected vagus and spinal nerves in HRP. If intrinsic sensory nerve cell bodies occur in the lung, the retrogradely transported HRP should be localized in the intrinsic airway ganglia. To study nerve fibers that originate from intrinsic airway ganglia, explants of airways will be cultured for 5 days, allowing extrinsic innervation time to degenerate. The VIP- and SP-containing nerve fibers that remain will be those that originate from intrinsic airway ganglia. Both fluorescence and ultrastructural immunocytochemical colocalization of VIP and SP in cultured and in noncultured (control) airways will be evaluated morphometrically to determine the distribution and morphological characteristics of intrinsic nerve fibers and terminals. These studies will provide fundamental information regarding the sensory and motor innervation in the airways with respect to VIP and SP.
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