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.

Human platelet reactivity with intact segments of rabbit aorta and selected regions of rabbit, rat and human aorta.

A technique measuring platelet reactivity with vessel wall subendothelium has been modified to examine platelet reactivity with vessel pieces in place of intact segments of aorta of a specific diameter. This modification of Baumgartner's original technique (1) allows measurement of blood platelet reactivity with vessel pieces, 5 X 10 mm in size, mounted on perfusion chambers with "twist bands." Adhesion and aggregation of human platelets to deendothelialized surfaces of intact segments of rabbit aorta and pieces of rabbit, rat and human aorta, were equivalent. This modification will expand the use of Baumgartner's technique to investigations of platelet vessel wall interactions using blood platelets and vessels from numerous experimental animal models and humans. It will also facilitate examination of possible differences in thrombogenocity of selected areas of vessels such as those exhibiting stages of atherosclerotic plaque formation.