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. Author manuscript; available in PMC: 2018 Nov 1.
Published in final edited form as: Anesthesiology. 2017 Nov;127(5):878–889. doi: 10.1097/ALN.0000000000001834

Table 1.

The influence of genotype and tolerance on morphine analgesia ED50.

Genotype ED50 morphine (mg/Kg) n number
WT 1.2 ± 0.1 29
MOP+/- opioid naive 5.9 ± 0.8* 15
MOP+/- opioid tolerant 38 ± 14# 8
β-arr2-/- 1.5 ± 0.4 16

Opioid tolerance was established in MOP+/- mice by 4 days of morphine (10 mg/Kg s.c.) injections.

*

p < 0.05 (unpaired t test vs WT);

#

p < 0.05 (unpaired t test vs MOP+/- opioid naïve).