PULMONARY VASOMOTOR RESPONSES OF ISOLATED PERFUSED CAT LUNGS TO ANOXIA AND HYPERCAPNIA

¹ Department of Physiology, University of Edinburgh

1. A method for perfusing isolated cats' lungs with the animal's own heparinized blood is described, with some observations on the condition of the lungs during and after perfusion.

2. The pulmonary vasomotor responses to inhalation of various gas mixtures have been studied during perfusion of the pulmonary vessels at constant volume inflow.

3. Inhalation of gas mixtures containing 5-10 per cent. CO₂ produces pulmonary vasoconstriction, as shown by an increase of pulmonary arterial pressure.

4. Inhalation of gas mixtures containing less than 15 per cent. O₂ also produces a pressor response.

5. Ventilation of the lungs with pure O₂ has no effect under the conditions of the experiments.

6. Ventilation of the lungs with pure neon or H₂ produces similar effects to that produced by pure N₂.

7. The pulmonary vasomotor responses to CO₂ and O₂ lack are not abolished by dihydroergotamine or atropine.

Note:

Some of the expenses of this research were met by part of a block grant from the Earl of Moray Fund.