Fig. 4.

Naloxone and HY6-F9 rapidly reverse fentanyl-induced oxygen saturation. Naïve rats were challenged with 0.1 mg/kg of fentanyl (s.c.), and 15 minutes post-fentanyl exposure, rats were given saline, naloxone either intravenously or subcutaneously, HY6-F9 intravenously, or naloxone + HY6-F9 intravenously. (A) Antinociception was measured 15 and 30 minutes postfentanyl exposure, and (B) oxygen saturation measured constantly by pulse oximetry for 10 minutes after rescue administration. (C) Inset to show detail of oxygen saturation from 15–20 minutes after fentanyl administration.