the inhibitory effect of morphine , nalorphine , oxymorphone , naloxone , naltrexone , n-methylnaloxone , levorphanol , levallophan , dextrorphan , dextrallophan , levo-methadone , dextro-methadone , pethidine , leu-enkephalin and u-50 488 on the acetylcholine ( ach ) -induced contraction of the toad rectus was investigated .
C0027358
naloxone
C0027360
naltrexone