Journal of Applied Physiology, Vol 55, Issue 2 427-432, Copyright © 1983 by American Physiological Society
Stimulation of splanchnic afferents reflexly relaxes tracheal smooth muscle in dogs
K. J. Rybicki, J. C. Longhurst and M. P. Kaufman
Although chemical stimulation of abdominal visceral afferents has been
shown to reflexly increase cardiovascular and ventilatory function, the
effect of stimulating these afferents on airway smooth muscle is unknown.
Therefore, we recorded transverse smooth muscle tension from an innervated
segment of trachea in chloralose-anesthetized dogs while we topically
applied capsaicin (200 micrograms/ml) and bradykinin (0.01-10
micrograms/ml) to the serosal surfaces of the stomach, small intestine, and
gallbladder. Application of these irritant substances to the stomach and
small intestine decreased tracheal tension and increased mean arterial
pressure. However, application of capsaicin and bradykinin to the
gallbladder had only small effects on both of these variables. Cutting the
splanchnic nerves abolished or greatly attenuated the decreases in tension
and increases in mean arterial pressure, whereas cutting the vagi had no
effect on them. We conclude that stimulation of splanchnic afferent endings
in the stomach and small intestine reflexly relaxes tracheal smooth muscle
in dogs. This effect may be one component of the constellation of autonomic
responses reflexly evoked by abdominal visceral pain and inflammation.
