Evidence for a spinal afferent innervation of the guinea pig lower respiratory tract as studied by the horseradish peroxidase technique.

The afferent innervation of the guinea pig lower respiratory tract was studied using a retrograde axonal transport technique with application of horseradish peroxidase (HRP) onto the lining respiratory epithelium. HRP-labeled cells were observed not only in the nodose ganglia but also in the jugular and upper thoracic dorsal root ganglia (mainly at the T2-T3 levels). Thus, both vagal parasympathetic and spinal sympathetic afferents seem to have peripheral branches close to or within the respiratory epithelium suggesting a dual sensory control of the airways.