The long term goals of this project are to identify the origins and distribution of peptide containing sensory and motor nerves in the airways. The basic hypothesis is that peptide containing nerve fibers supplying the airways originate from nerve cell bodies located in sensory ganglia, and from postganglionic nerve cell bodies located in sympathetic ganglia and 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 s transported through the axons to nerve terminals in the lung). The distribution of sympathetic nerve fibers will be studied by WGA injections into the superior cervical, stellate, and upper throacic ganglia of the sympathetic chain. The fibers will be identified in the airways and characterized as to their peptide content, distribution, and ultrastructure. Once nerve terminals are identified, the peptide content of the same nerve terminal will be determined by colocalization with immunocytochemistry. The ultrastructural features of specific sensory or sympathetic nerve terminals will also be examined. To study nerve fibers that originate from intrinsic airway ganglia, explants of airways will be cultured for 5 days, allowing time for extrinsic innervation to degenerate. The peptide-containing nerve fibers that remain will be those that originate from intrinsic airway ganglia. Both fluorescence and ultrastructural immunocytochemical colocalization of peptides in cultured and in noncultured (control) airways will be evaluated morphometrically to determine the distribution and morphological characteristics of intrinsic nerve fibers and terminals. The intrinsic airway ganglia will also be investigated using neurophysiological methods. In these studies, neurons in tracheal paraganglia will be maintained in short term organ baths. The individual neurons will be penetrated with a recording electrode. Nerve facicles along the paratracheal chain will be stimulated electrically while recording from the neurons. After the electrophysiological characteristics are determined, a neural tracing material will be injected into the neuron. The distribution, ultrastructure, and peptide content will be correlated with the electrical properties of the identical neuron. These studies will provide fundamental information regarding the sensory and motor innervation in the airways with respect to peptides.
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