Figure 1. Carotid body-mediated augmentation of ventilatory CO₂ chemosensitivity measured during rebreathing.

A, representative traces showing increasing percentage inspired CO₂ (upper trace) and corresponding spontaneous, integrated tracheal airflow (lower trace) during a single rebreathing experiment in one animal. Inspiratory and expiratory flows were separately integrated and depicted in a single trace with + indicating inspiratory volume and − indicating expiratory volume. Timescale expanded at right side. B, breath by breath against percentage CO₂ in a single sham animal, during euglycaemia (•; from the example data shown in A) and hypoglycaemia (○). increased linearly with increasing CO₂ (P < 0.0001; linear regression), and the ventilatory CO₂ sensitivity was taken as the slope of the regression. During insulin-induced hypoglycaemia there was an increase of ventilatory CO₂ sensitivity. C, breath by breath against percentage CO₂ in a single CSNX different animal, during euglycaemia (•), and hypoglycaemia (○). increased linearly with increasing CO₂ (P < 0.0001; linear regression) but the ventilatory CO₂ sensitivity did not change during hypoglycaemia.