Airway vagal afferent fibers adapt either rapdily or slowly in response to mechanical stimulation. To investigate the mechanism of this response, our laboratory has established an in vitro model. The guinea pig trachea and its vagal innervation, including the nodose and jugular ganglia, were isolated, then superfused at 37°C with buffer solution. Action potentials were evoked by mechanical stimulation (via a blunt rod attached to a force transducer) and recorded with an extracellular micorelectrode placed near cell bodies in either the nodose or jugular ganglion. 11 out of 12 Aδ fibers with their cell bodies in the nodose ganglion adapted rapidly to mechanical stimuli, whereas 9 of 10 fibers with cell bodies in the jugular ganglion (6 C-fibers and 4 Aδ fibers) adapted slowly. Consistent with the rapidly adapting response of the nerve terminal, intracellular recordings from neurons in the nodose ganglion revealed rapidly adapting responses to suprathreshold current steps. This rapidly adapting pattern of action potential discharge was shifted to a slowly adapting pattern by 4-aminopyridine (4-AP, 10 μM). However, this 4-AP-sensitive current did not appear to regulate adaptation to mechanical stimuli at the nerve ending, as 4-AP applied to the trachea did not affect the discharge pattern. Tetraethyl ammonium (TEA), apamin, and charybdotoxin also did not affect the response of the nerve endings. We conclude that the ganglionic orgin of the cell body is the primary predictor of the adaptation response of guinea pig tracheal afferent neurons. Moreover, while the rapidly adapting nerve endings had cell bodies that also adapted rapidly to intracellular current steps, these properties may be governed by different ionic mechanisms.
|Original language||English (US)|
|State||Published - Mar 20 1998|
ASJC Scopus subject areas
- Molecular Biology