the respiratory and cardiovascular effects of the highly selective mu opioid agonist , d-ala2 , mephe4 , gly- ol5 enkephalin ( dago ) and the relatively selective delta agonist , d-leu5 enkephalin ( dadl ) were compared following injection ( 0.1 microliter ) into the nucleus ambiguus ( na ) of spontaneously-breathing and artificially-respired , pentobarbital-anesthetized rats .
C0525773
dago
C0014298
enkephalin