Pharmacological profiles of beta-funaltrexamine (beta-FNA) and beta-chlornaltrexamine (beta-CNA) on the mouse vas deferens preparation.

The profiles of action of beta-funaltrexamine (beta-FNA) and beta-chlornaltrexamine (beta-CNA) have been assessed in the mouse vas deferens preparation. beta-FNA, but not beta-CNA, demonstrated a reversible agonist action that appeared to be mediated via kappa-receptor interaction. beta-CNA produced an irreversible antagonism of mu-, kappa- and delta-mediated agonist actions, whereas beta-FNA irreversibly antagonized mu-mediated agonist effects only. This selective action of beta-FNA could also be seen following administration in vivo. beta-CNA and particularly beta-FNA should prove valuable in the elucidation of multiple opioid receptors.