Presence of peripheral-type benzodiazepine binding sites on human erythrocyte membranes.

A nanomolar affinity peripheral-type benzodiazepine binding site is described in human erythrocyte membranes. [3H]PK 11195 is displaced from this binding site by unlabeled drugs with the rank order PK 11195 greater than Ro 5-4864 greater than flunitrazepam much greater than clonazepam. Neither GABA nor a non-hydrolyzable analog of GTP have an effect on binding parameters. These data provide evidence that a peripheral-type benzodiazepine binding site, pharmacologically similar to the intracellular binding site described in other tissues, is present in the plasma membrane of human erythrocytes.