Possible role of the non-opioid dynorphin A-(1–13) receptor in the inhibition of [ 3H]noradrenaline uptake in rat heart

Abstract

Recently, our laboratory has demonstrated the presence of low affinity and hiBh capacity non-opioid binding sites for [ 3 H]Dynorphin A-(1-13) ([ 3 H]Dyn A-(1-13)) in membrane preparations of rat heart (1). In order to determine if these sites could be linked to some cardiovascular function, we measured the effects of Dyn A and related peptides as well as selective κ, μ and δ opioid receptor ligands on the uptake of [ 3 H]noradrenaline ([ 3 H]NA) in a heart synaptosomal-mitochondrial fraction. The uptake of [ 3 H]NA was temperature, Na + and nisoxetine sensitive and blocked by Dyn A and related peptides. A good correlation (r=0.96) was established between the ability of the peptides to inhibit [ 3 H]NA uptake and to compete with the binding of [ 3 H]Dyn A-(1-13) to non-opioid sites