Hypertonicity activates pulmonary vagal afferents independently of vasoconstriction

► Injecting hypertonic saline into the lung stimulates breathing by a vagal reflex. ► We determined if the reflex is due to increased fluid flux from vessels to alveoli. ► Decreasing lung local perfusion by vasoconstriction reduces fluid flux. ► Vasoconstriction around the sensory ending did not alter the reflex. ► Thus, increased transvascular fluid flux is unlikely to be the stimulatory mechanism.