Abstract

In vitro electrophysiological techniques were used to examine the effect of bradykinin on guinea pig trachea and bronchus afferent nerve endings arising from the nodose or jugular ganglia. The data reveal that bradykinin activates nerve terminals of jugular C and Aδ fibers. Although the fibers were too few in number to study rigorously, bradykinin also stimulated nodose C fibers innervating the trachea and bronchus. In contrast, Aδ fibers arising from the nodose ganglion were unresponsive to bradykinin challenge. The responses in both jugular C and Aδ fiber types were blocked by a selective bradykinin B₂ receptor antagonist and were not dependent on the efferent release of sensory neuropeptides. These data indicate that the sensitivity of guinea pig airway afferent fibers to bradykinin is dependent more on the ganglionic origin of the cell body than on the conduction velocity of its axon.