The cross talk between different membrane receptors is the source of increasing research. We designed and synthesized a new hetero-bivalent ligand that has antagonist properties on both A(1) adenosine and mu opiate receptors with a K(i) of 0.8+/-0.05 and 0.7+/-0.03 microM, respectively. This hybrid molecule increases cAMP production in cells that over express the mu receptor as well as those over expressing the A(1) adenosine receptor and reverses the antalgic effects of mu and A(1) adenosine receptor agonists in animals.