NITRIC-OXIDE SYNTHASE IN VAGAL SENSORY AND SYMPATHETIC NEURONS INNERVATING THE GUINEA-PIG TRACHEA

Sympathetic (stellate and superior cervical ganglion) and sensory vaga l (nodose and jugular ganglion) neurons innervating the guinea-pig tra chea were labelled using a retrograde neuronal tracer (Fast Blue) and tested for immunoreactivity to nitric oxide synthase (NOS) and either tyrosine hydroxylase (TH; sympathetic ganglia) or substance P (SP; vag al afferent neurons). Approx. 3% of the sympathetic neurons innervatin g the trachea were NOS-positive. These neurons belonged to the non-cat echolaminergic phenotype. Amongst the retrogradely labelled neurons in the vagal sensory ganglia, 5-10% of retrogradely labelled neurons in the nodose (inferior vagal) ganglion, and 10-20% of those in the jugul ar (superior vagal) ganglion were NOS-immunoreactive. All NOS-positive vagal afferent neurons labelled with retrograde tracer were negative for substance P. Accordingly, the results of these studies provide evi dence that portions of the sympathetic and sensory innervation of the guinea-pig trachea is provided by NOS-immunoreactive neurons.