EFFECTS OF MU-OPIOID, DELTA-OPIOID AND KAPPA-OPIOID ANTAGONISTS IN ATRIAL PREPARATIONS FROM NONFAILING AND FAILING HUMAN HEARTS

1. We examined the effects of naloxone (preferentially mu-antagonist), naltrindole (selective delta-antagonist) or nor-binaltorphimine (nor- BNI, selective kappa-antagonist) on auricular myocardium tissue from n onfailing and failing human hearts. 2. The opioid antagonists used in this study induced inhibitory effects in auricular strips from failing and nonfailing human hearts. In addition, the maximal effect, the IC5 0, and the slope of concentration-response curves obtained with mu-, d elta-, and kappa-opioid antagonists were similar in failing and nonfai ling human heart tissues. 3. The kappa-antagonist was more effective t han naltrindole or naloxone. Moreover, the IC50 for nor-BNI (0.25 +/- 0.01 x 10(-5) M) was lower than the IC50 for naloxone (26.5 +/- 5.0 x 10(-5) M) and naltrindole (13.8 +/- 2.0 x 10(-5) M). Similar results w ere obtained in auricular strips from failing human hearts. 4. Our res ults demonstrate that the failing heart does not modify the inhibitory cardiac effects obtained with selective opioid antagonists. Copyright (C) 1997 Elsevier Science Inc.