Journal of Applied Physiology, Vol 56, Issue 3 737-745, Copyright © 1984 by American Physiological Society
Effects of dopamine, isoproterenol, and lobeline on cranial and phrenic motoneurons
E. van Lunteren, M. A. Haxhiu, J. Mitra and N. S. Cherniack
Recent studies have suggested that the upper airway muscles receive a
substantial portion of their excitatory input from the peripheral
chemoreceptors. We examined the responses of the phrenic, hypoglossal, and
recurrent laryngeal nerves to agents that are known to modify carotid body
activity. Dopamine, an inhibitor, and isoproterenol and lobeline, two
stimulators of carotid body activity, were administered into the lingual
arteries of 14 anesthetized, paralyzed cats artificially ventilated with
100% O2. Dopamine decreased the activity of all three nerves (P less than
0.001) but inhibited the hypoglossal nerve more than the phrenic and
recurrent laryngeal nerves (P less than 0.001). Isoproterenol and lobeline
increased the activity of all three nerves (P less than 0.001) but
stimulated the hypoglossal nerve more than the phrenic and recurrent
laryngeal nerves (P less than 0.001). These relatively greater effects of
all three agents on the hypoglossal nerve compared with the phrenic and the
recurrent laryngeal nerves persisted under both hypoxic and hypercapnic
conditions. After midcervical vagotomy, the responses of the hypoglossal to
all three drugs remained larger than those of the phrenic nerve. After
combined vagotomy and carotid sinus nerve section, the stimulatory effects
of lobeline and the inhibitory effects of dopamine were no longer apparent.
We conclude that it is possible to preferentially alter respiratory-related
activity of the hypoglossal nerve compared with that of the phrenic nerve
using agents that modify peripheral chemoreceptor activity.
