A RETROGRADE LABELING TECHNIQUE FOR THE FUNCTIONAL-STUDY OF AIRWAY-SPECIFIC VISCERAL AFFERENT NEURONS

The development of a method is described whereby primary afferent neur ons that specifically innervate the airways in the guinea pig can be r etrogradely labeled, acutely dissociated and studied functionally with electrophysiological techniques. Following administration of either d extran-tetramethylrhodamine, Fast Blue, or Fluorogold dye into the tra cheal lumen, dye-labeled neurons can be visualized in 100-mum serial n odose ganglion sections. Control experiments show that labeling does n ot result from the undesirable spread of the dyes to target innervatio n fields in the gastrointestinal (GI) or cardiovascular (CV) systems. Neuronal somata retain dye label when acutely dissociated. Microelectr ode studies provide evidence that the presence of the Rhodamine dye la bel and its fluorescent excitation neither alter basic electrophysiolo gical membrane parameters nor the chemoreceptive properties of isolate d neurons. Thus this new method will allow the isolation of individual airway-specific primary visceral afferent neurons for functional stud ies with multidisciplinary techniques.