release was also inhibited ( maximally by 40-50 % ) by morphine ( ec50 = 5-10 nm ) , [ leu5 ] enkephalin ( ec50 = approximately 300 nm ) , [ d-ala2 , d-leu5 ] enkephalin ( dadle ) , and tyr-d-ala-gly- ( nme ) phe-gly-ol ( dago ) ( ec50 values = approximately 30 nm ) .
C0014298
enkephalin
C0525773
dago