Influence of cervical sympathetic nerves on ventilation and upper
airway resistance in the rat
K.D. O'Halloran*, A.K. Curran**, A. Bradford+
Influence of cervical sympathetic nerves on ventilation and upper airway resistance in the
rat. K.D. O'Halloran, A.K. Curran, A. Bradford. ©ERS Journals Ltd 1998.
ABSTRACT: The cervical sympathetic trunks innervate the carotid bodies, carotid
baroreceptors, thyroid gland and the upper airway mucosa, structures which can
influence breathing and upper airway resistance. (same in humans)
However, their role in the control of ventilation and upper airway patency
is poorly understood.
A constant airflow was applied to the upper airway through a high-cervical trache-
ostomy in anaesthetized rats breathing spontaneously through a low-cervical trache-
ostomy. The peripheral ends of the cut cervical sympathetic trunks were stimulated
electrically and airflow resistance and ventilation were measured. The effects of cervi-
cal sympathetic trunk section on ventilation were also measured in conscious rats.
In conscious rats, cutting the sympathetic trunks caused a decrease in ventilation
during normoxia but only slightly affected ventilatory responses to hypoxia and
hypercapnia. In anaesthetized rats, sympathetic trunk stimulation caused an inhibi-
tion of breathing which was sometimes followed by excitation. These responses were
unaffected by α- or β-adrenoceptor blockade but were abolished by cutting the
carotid sinus nerves. Sympathetic stimulation also caused a fall in upper airway
resistance which was reduced by bypassing the nose, unaffected by propranolol or
carotid sinus nerve section and abolished by phentolamine.
It was concluded that the cervical sympathetic nerves exert important influences
on ventilation and upper airway resistance.
Eur Respir J 1998; 12: 177–184.
