Histamine-induced reflex tracheal constriction is attenuated by hyperoxia and exaggerated by hypoxia.

摘要: Abstract The effect of vagal reflexes on bronchomotor tone can be altered by their interaction with other factors, such as the prevailing state oxygenation. In anesthetized, paralyzed, and artificially ventilated dogs, a reflex constriction was induced in an isolated tracheal segment administration aerosolized histamine to lungs. When challenge repeated during hypoxic conditions (PaO2, 45 mmHg), magnitude response significantly larger than normoxia. contrast, hyperoxia 344 smaller normoxic response. changes oxygenation were done under isocapnic isohydric conditions. Hyperoxia alone had no upon baseline tone, whereas hypoxia caused increase approximately half animals. not affected changes. We think that potentiating effects attenuating are mediated between lung sensory receptors carotid body chemoreceptors.