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. Author manuscript; available in PMC: 2008 Dec 1.
Published in final edited form as: Anesth Analg. 2008 Jun;106(6):1873–1881. doi: 10.1213/ane.0b013e31817300be

Figure 4.

Figure 4

Effects of opioid receptor antagonists on the antinociception of intrathecal administration of endomorphin-1 (30 μg) and endomorphin-2 (30 μg) in the rat formalin assay. Sterile water (vehicle 1 mL/kg), naltrexone (NTX 0.1 mg/kg), or naltrindole (NTI ± mg/kg) was administered subcutaneously 30 min before intrathecal administration of endomorphins. Nor-binaltorphimine (nor-BNI 10 mg/kg) was administered subcutaneously 24 h before endomorphins. Ordinates: Total flinches during the phase 1 (0–10 min, top panel) and phase 2 (11–40 min, bottom panel) after administration of formalin. The asterisks represent a significant difference from the vehicle-pretreated group condition (P < 0.05). See Figure 3 for other details.