PULMONARY VASOMOTOR FIBRES IN THE SYMPATHETIC CHAIN AND ITS ASSOCIATED GANGLIA IN THE DOG

Abstract

In the perfused living animal, under conditions which eliminate cardiac and bronchomotor effects, stimulation of the upper thoracic sympathetic chain, the stellate ganglion, the middle cervical ganglion, and the thoracic vagosympathetic nerves causes a rise in pulmonary arterial pressure of 10–15 per cent. at constant pulmonary blood inflow. More rarely a fall in pulmonary arterial pressure takes place. Stimulation of these same nerve structures at constant pulmonary arterial pressure perfusion may cause a diminution in lung blood‐flow by as much as 30 per cent. The rise in pulmonary arterial pressure is not due to changes in the amount of blood transferred from the bronchial to the pulmonary vascular bed, nor is it dependent upon the method used for artificial ventilation of the lungs. Results are described which are consistent with the view that the upper thoracic chain, stellate ganglion or middle cervical ganglion, and thoracic vagosympathetic nerves constitute a pre‐ganglionic‐ganglionic‐post‐ganglionic path for adrenergic pulmonary vasoconstrictor fibres. The same path probably carries pulmonary vasodilator fibres, the nature of which is discussed.