The general aim of this project is to improve electrical measurements of excitable membrane characteristics consistent with physical and chemical methods for the study of nerve and muscle membrane ionic channels. Two major approaches are used. The first involves a rapid analysis of ionic channel conductances by means of computer controlled voltage clamp techniques. This approach is concerned with the development of modern methods and systems for controlling voltage clamp experiments on-line and acquiring excitable membrane conductance data in a form that can be analyzed by digital computing machines. Programs for carrying out this analysis are developed. The second approach involves a steady-state analysis of excitable membrane characteristics by means of impedance measurements. Improvement of bridge impedance techniques to achieve greater accuracy is sought. Impedance measurements are made on giant axons and an investigation of effects of polarizations for comparison with step and ramp techniques and ion conduction models is carried out. This project is supportive of a number of other projects in terms of the development of relevant hardware and software.