this posttetanic inhibition was largely attenuated or even reversed into potentiation if tested in the presence of ketocyclazocine ( 40 nmol/l ) or pentazocine ( 0.3 and 3 mumol/l ) and also methionine-enkephalin ( 0.2 and 2 mumol/l ) or morphine ( 1 mumol/l ) while it was not affected in the presence of leucine-enkephalin ( 2 mumol/l ) or d-ala2-d-leu5-enkephalin ( 40 and 400 nmol/l ) .
C0014294
leucine-enkephalin
C0014298
enkephalin