Bidirectional effect of naloxone on emotionally conditioned digitalis toxicity

Naloxone affected latency to digitalis toxicity in guinea pigs with prior exposure to Pavlovian fear conditioning but not in controls. The effect was bidirectional depending on dose: guinea pigs given low doses of naloxone were protected from the emotionally conditioned effect wile others, given high doses of the drug, succumbed to digitalis toxicity faster.