Nasal vasomotor oscillations in the cat associated with the respiratory rhythm.

Asymmetrical nasal vasomotor oscillations mediated via the cervical sympathetic nerve have been observed in the spontaneously breathing cat. The vasomotor activity persists after abolition of spontaneous respiration with a neuromotor relaxant agent indicating that the vasomotor activity originates in the respiratory areas of the brain and is not due to any of the mechanical effects of respiration. The nasal vasomotor activity is abolished on hyperventilation indicating that it may be driven from a central respiratory oscillator. The vasomotor activity exhibits a reciprocal activity with oscillations in sympathetic activity alternating from one nasal passage to the other and this may be due to a direct relationship with a nasal cycle in the cat.