New method for perfusing bronchial arteries: histamine bronchoconstriction and apnea.

Abstract

A metal tube, with a lumen wide enough to allow adequate aortic flow, was inserted into the thoracic aorta via the abdominal aorta in paralyzed, artificially ventilated dogs. Inflated balloons around each end of the tube isolated from the systemic circulation the aortic segment with the first 5 aortic intercostal arteries, from which the bronchial arteries arise. Histamine injected into this aortic segment increased pulmonary resistance (RL), decreased dynamic pulmonary compliance (CL), and constricted a segment of cervical trachea isolated from the lower airways and lungs. The changes in RL and CL when histamine was injected into the bronchial arteries were apparently due to a reflex constriction of the conducting airways, while the changes after right atrial injections were due to direct constriction of alveolar ducts and respiratory bronchioles supplied by the pulmonary circulation. In spontaneously breathing dogs, histamine injected into the bronchial arteries caused either decreased tidal volume or apnea; this was occasionally preceeded by a deep inspiration and small expiratory movements.