This project is concerned with the elucidation of the molecular mechanisms for some of the pharmacological actions of local anesthetics. Although local anesthetics are primarily known for their ability to block nerve conduction, their characterization as """"""""anesthetics"""""""" implies that they have a generalized action as inhibitors of cellular responses to stimulation. In fact local anesthetics do inhibit a wide variety of cellular functions including active and passive transport of ions, synaptic transmission, contractility of muscle, non-muscle cell motility and aggregation, cytoskeletal organization, lipolysis, etc. Many of the processes inhibited by local anesthetics are known or believed to be dependent on CA++, and the effect of CA++ as a regulator is expressed in many cases through its combination with the protein calmodulin. The calmodulin-CA++ complex is a regulator of many cellular processes and enzymes. We have recently discovered that local anesthetics are antagonists of calmodulin-CA++ mediated activation of several enzymes. In these studies we will investigate the mechanism of action of the anticalmodulin activity of local anesthetics on several enzyme systems including Ca/Mg ATPase, cyclic nucleotide phosphodiesterase and myosin light chain kinase and the calmodulin-activated phosphorylation of the acetylcholine receptor which we have also recently discovered. Other studies will concern the action of local anesthetics on membrane ion channels utilizing intact cells and model systems composed of liposomes containing pure proteins (e.g. Band 3 protein of the red cell) that serve as the channels for ion movement. An important aim of this project is to relate the biochemical actions of local anesthetics to their effects on the functions of intact cells.
