Figure 4.

Hypercapnia fails to trigger expiratory activity following acute inhibition of AlstR-expressing Phox2b neurons in the ventrolateral brainstem in anesthetized rats. Time-condensed record (top traces) illustrating changes in integrated PN amplitude and abdominal EMG in response to repeated increases in the level of inspired CO₂ in the absence and presence of allatostatin (10 μm) on the ventral brainstem surface in an animal transduced with PRSx8-AlstR-EGFP-LV. Expanded time base recordings of PN and abdominal EMG are shown below, illustrating late-expiratory abdominal activity evoked by hypercapnia and reversibly blocked by allatostatin application to the ventral brainstem.