[3H]-SKF 10047 binding to rat brain membranes: evidence for kappa isoreceptors.

Studies of the binding of [3H]-SKF10047 to rat brain membrane preparations revealed a binding site which possessed high affinity for kappa and agonist/antagonist analgesics. However, this site was distinguished from kappa sites labelled with [3H]-ethylketazocine by its high affinity for Met5-enkephalin Arg6.Phe7 and beta-endorphin as well as its low affinity for dynorphin 1-13. We therefore tentatively suggest that this may represent a possible kappa isoreceptor population.