Purified sodium channels from rat sarcolemma will be reconstituted into artificial membranes for biophysical studies. Using patch clamp techniques single channel currents from purified sodium channels will be recorded under pharmacological condiltions successfully used for flux studies with this channel. A major aim of this study is to demonstrate the reconstitution conditions necessary for observing the voltage dependent activation and inactivation characteristic of the in situ sodium channel. Reconstituted sodium channels will be characterized with respect to cation selectivity, temperature dependence, conductivity, ion interactions, roles of surface charge and membrane lipids, kinetics of gating, etc. Successful completion of this project is a prerequisite of long term objectives to study the molecular structure-function relationships of sodium channels and to unravel the biophysical details of sodium channel function in a system more amenable to experimental manipulation than native membranes. Information gleaned from the study of sodium channels in artificial membranes can provide insights into unrecognized pathophysiology of neuromuscular disease.
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