Our main objective is to understand the relationship between membrane control of ionic movements especially calcium and the regulation of the function of excitable cells as related to the action of pharmacological agents that modify neuronal or muscle function. The systems under study are excitation coupling mechanisms in nerve and muscle. At present we are concentrating on three areas; (1) excitation-respiration coupling in skeletal muscle, (2) the interaction between calcium and local anesthetics in nerve, and (3) the factors that couple calcium influx with efflux in cardiac, skeletal, and smooth muscle.