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

Abstract

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. CO 2 produces pulmonary vasoconstriction, as shown by an increase of pulmonary arterial pressure. 4. Inhalation of gas mixtures containing less than 15 per cent. O 2 also produces a pressor response. 5. Ventilation of the lungs with pure O 2 has no effect under the conditions of the experiments. 6. Ventilation of the lungs with pure neon or H 2 produces similar effects to that produced by pure N 2 . 7. The pulmonary vasomotor responses to CO 2 and O 2 lack are not abolished by dihydroergotamine or atropine.