Effect of vagotomy and vagal stimulation on lung mechanics and circulation

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Abstract
In sheep, anesthetized and intubated, bilateral cervical vagotomy produced no change in lung compliance (Cl), reduced inspiratory resistance to airflow, increased expiratory resistance to airflow, and changed the pattern of breathing. Electrical stimulation of the peripheral end of the cut vagus nerve produced an immediate increase in lung volume due to an increase in inspiratory tonus, a fall in Cl, an increase in resistance to airflow, and a decrease in heart rate and systemic arterial pressure. Pulmonary arterial pressure remained unchanged; pulmonary arterial resistance increased. These effects were blocked by atropine. The lung mechanics changes were partly reversed spontaneously, completely reversed by forced inflation, and potentiated by prostigmine. The effects on lung mechanics suggest that vagal stimulation in the sheep mainly affects the peripheral airways producing airway closure, and indicates the possibility of a nervous mechanism for the control of the number of ventilated lung units. compliance; total pulmonary resistance; inspiratory; tonus; peripheral airway reaction; respiratory pattern Submitted on December 6, 1962