Recovery of Chemosensory Function of Regenerating Carotid Nerve Fibers

Abstract

The site at which physiological stimuli elicit carotid nerve activation is still disputed. To evoke an increase in discharge in slowly adapting receptors (such as carotid body chemoreceptors), stimuli must depolarize the sensory endings. Although hypoxia can depolarize nerve membranes (8), hypercapnia has the opposite effect (9). Furthermore, high acidity is required to alter nerve membrane potentials (15) or the generation of baroreceptor impulses (6). Thus to postulate a direct action of small changes in PO₂, PCO₂, and pH on carotid body sensory endings, one has to assume that these terminals are quite different from others. The idea that carotid body nerve endings do not possess specific chemosensitivity has been further sustained by successful functional reinnervation of carotid bodies with vagal (2) and superior laryngeal nerve fibers (18).

This work was supported by grants N0-05666, N0-07938, and N0-10864 from the U.S. Public Health Service. Thanks are due to Mrs. Caroline Zapata for preparation of the figures.