So far, the effects of high voltage electrical fields on membrane proteins, including functional changes and conformational damage, have not been clearly defined. In addition, no therapy exists at present for electrically damaged membrane proteins. The primary goal of this proposed project is to gain a better understanding of the molecular mechanisms of electrical injury; specifically, to focus on the voltage-gated ion channels and charge movements across the transverse tubular (T-tubular) membranes of skeletal muscle cells. The preliminary results have demonstrated several electrical shock-induced functional changes: l) voltage-gated K+ channel conductance in frog skeletal muscle fibers can be reduced, temporarily or permanently, by electrical shocks, depending on the magnitude and duration of the shock pulses; 2) the ionic selectivity of K+ channels is reduced by electrical shock, resulting in a depolarization shift in the membrane resting potential; 3) voltage-gated ion channels can protect the phospholipid bilayer from the effects of electroporation. Areas I focus on are: ion channel activation, inactivation, ionic selectivity, gating systems, charge movements on the T-tubular membrane, pharmacologic effects, and the effects of a weak alternating current electrical field. The major points of the proposed project are to study the locations of post-shock conformational damage and develop methods to restore damaged ion channel proteins. Through the study of gating currents damaged protein subgroups can be localized in channel pores or in voltage sensor regions. By changing the polarity of the electrical shock field, damage to surface membrane and that to the T-tubular membrane can be separated. Several toxins which have been shown to bind to specific groups of Na+ channels in nerve and some muscle cells will be applied to skeletal muscle cell membrane before and after an electrical shock. By comparison with shock-induced effects, similar effects would suggest the involvement of the same or a nearby protein subgroup. Combining the results of functional studies and pharmacologic experiments, an understanding of the functional defects correlated with to conformational changes in protein molecules can be obtained. Then a weak alternating current electrical field which are known to affect some protein functions will be applied on damaged membrane protein. It may be possible to design biochemical treatments and physical therapy to facilitate cell function recovery.
