4923
After determining isoflurane MAC in triplicate , birds were given a mu - opioid agonist ( morphine , n = 9 ) or a kappa - opioid agonist ( U50488H , n = 9 ) .
 None
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: GENE 
Text: {0} 
Answer:
 None