the irreversible non-selective opioid antagonist beta-chlornaltrexamine ( beta-cna ) was used in combination with selective mu receptor protection by [ d-ala2 , mephe4 , gly ( ol ) 5 ] enkephalin ( dago ) to produce an effective kappa receptor antagonism in the guinea-pig field-stimulated ileum preparation .
C0014298
enkephalin
C0525773
dago