Peripheral benzodiazepine binding sites in heart and their interaction with dipyridamole

Specific binding of [3H]diazepam to rat and guinea-pig heart tissue has been found. These binding sites are similar to those in lung, liver, kidney and mast cells but differ from those in the brain. Dipyridamole interacts with this receptor and is several fold more potent as a displacer of [3H]diazepam bound to heart preparations than to brain membranes. Specific binding per unit protein in the left ventricle, right ventricle and interventricular septum is significantly higher than in the left and right atrium.