Figure 1.

Opioid receptor mechanisms at the preBötC modulate breathing in vivo. A, Schema and histological section showing unilateral location of the tip of the microdialysis probe (arrow) in the medulla. B, Example showing that addition of 5 μm DAMGO to the aCSF perfusing the preBötC caused respiratory depression, effects that were reversed with naloxone. C, Group mean data (n = 9) for the effect of DAMGO (5 μm), and then the subsequent reversal of effects with naloxone (100 μm), on respiratory rate, duration of inspiration, duration of expiration, the amplitude of diaphragm (Dia) muscle activation, the amplitude of genioglossus (GG) muscle activation, and respiratory rate variability. Error bars are SEM. D, DAMGO (200 μm) caused complete respiratory arrest in the anesthetized adult rat. The animal was kept alive by artificial ventilation, and respiratory activity recovered after 30 min of perfusion with naloxone (100 μm). *p < 0.05, significant differences compared with aCSF controls. na, Nucleus ambiguus; io, inferior olive.