STRUCTURE-FUNCTION RELATIONSHIPS IN THE AIRWAYS: BRONCHOCONSTRICTION MEDIATED VIA VAGUS NERVES OR BRONCHIAL ARTERIES; PERIPHERAL LUNG CONSTRICTION MEDIATED VIA PULMONARY ARTERIES,
Abstract:
Reflex bronchoconstriction, mediated via vagal efferent nerve fibers is characterized by increased R sub L, decreased V sub D, with no significant change in static C sub L. Anatomic studies performed during electrical stimulation of the peripheral ends of the cut cervical vagus nerves showed constriction of large airways with no changes in the peripheral airways. Injection of serotonin in the bronchial arteries resulted in changes in the mechanical properties of the lungs similar to vagal stimulation, presumably by a local action of the drug on the airways perfused by the bronchial arteries. Injection of barium sulfate microemboli into the pulmonary arteries increased R sub L and V sub D but decreased C sub L, presumably by releasing histamine. Right-sided injection of histamine or 4880 resulted in similar effects. Anatomic studies showed that the principal site of constriction was the alveolar ducts. Author