Properties of a local anesthetic receptor in rat brain

Saturable binding of local anesthetics in rat brain homogenates was demonstrated using (14C)-lidocaine and (3H)-bupivacaine. Saturation analyses revealed a single class of binding sites for lidocaine and bupivacaine. A series of drugs with local anesthetic properties inhibited this binding, while drugs without local anesthetic activity did not affect the specific binding. Specific binding of lidocaine and bupivacaine was maximal from pH 8 to 10; the pH versus binding profile was similar to that reported for local anesthetic blocking of peripheral nerve conduction. These characteristics suggest that binding of local anesthetics to this or similar sites mediates their pharmacological activity.