Fig. 2.
Representative recordings exhibiting the impact of systemic (d-Ala2,N-Me-Phe4,Gly-ol)-enkephalin (DAMGO; 100 μg/kg) on hypoxia (A)- or hypercapnia (B)-induced changes in sigh number and amplitude. In each panel, the chemical challenges (10% O2 for 1.5 min and 7% CO2 for 4 min) were applied before (left) and 5 min (center) and 30 min (right) after systemic DAMGO. Traces from top to bottom are arterial blood pressure (BP), Vt, and end-tidal pressure of carbon dioxide (PetCO2), with stimulating durations of chemical challenges indicated.