The opioid antagonist activities of two bivalent ligands, BNI and nor-BNI, have been evaluated in smooth muscle preparations and in mice. Both ligands are highly potent and selective as k opioid receptor antagonists, with relatively feeble blocking activity at μ and δ opioid receptors. BNI and nor-BNI represent the first highly selective k opioid receptor antagonists and should be of great utility as molecular probes for identifying the interaction of agonist ligands with k opioid receptors in vitro and in vivo.
Bibliographical noteFunding Information:
This investigation was supported by the National Institute on Drug Abuse. We thank Michael Powers, Barbara Taylor and Mary ~chwartz for their competent technical assistance.