Journal of Applied Physiology, Vol 63, Issue 5 1781-1787, Copyright © 1987 by American Physiological Society
Effects of unilateral vagal stimulation on intrapulmonary neuroepithelial bodies
J. M. Lauweryns, V. de Bock and M. Decramer
Laboratorium voor Histopathologie, Faculteit Geneeskunde, Katholieke Universiteit te Leuven, Belgium.
We studied the influence of unilateral vagal stimulation on intrapulmonary
neuroepithelial bodies (NEB) in rabbits. The left vagus nerve was cut and
electrically stimulated for 10 min. Animals were killed and the lungs
studied with fluorescence and electron microscopy. Intensity of
formaldehyde-induced fluorescence, which reflects the serotonin content in
NEB, was higher on the stimulated side than on the nonstimulated side (118
+/- 7 vs. 100%, n = 8, P less than 0.001). The latter difference was found
to correlate with the stimulus amplitude (r = 0.9, P less than 0.05).
Ultrastructurally a decrease in the number of exocytotic dense-cored
vesicle (DCV) profiles at the level of the NEB basal epithelial cell
membrane was found on the stimulated side (0.32 +/- 0.10 vs. 0.45 +/- 0.16
DCV/micron of basal epithelial cell membrane, n = 8, P less than 0.05).
Section of the left vagus nerve without electrical stimulation affected
neither the fluorescence intensity nor the number of exocytotic DCV
profiles. In animals with supranodosal or infranodosal chronic vagotomy the
observed effects of unilateral vagal stimulation were no longer present. We
conclude that 1) vagal stimulation increases the serotonin content of NEB;
2) it decreases the number of exocytotic DCV profiles; 3) this effect
depends on the amplitude of the stimulus; 4) it is obtained through
efferent vagal fibers; 5) these results are the opposite of the effects
seen after exposing normal NEB to acute hypoxia; and 6) these physiological
experiments corroborate a vagal innervation of NEB, which may play an
important role in modulating the sensitivity and reaction of NEB to various
stimuli.
