ELECTROMEDIATED PERMEABILIZATION OF FROG SKELETAL-MUSCLE CELL-MEMBRANE - EFFECT OF VOLTAGE-GATED ION CHANNELS

The asymmetrical electromediated permeabilization of cell membranes of frog skeletal muscle fibers with respect to the stimulation pulse polarity were studied using an improved double Vaseline gap voltage clamp. Channel-mediated currents in response to a variety of high voltage electrical pulses have been differentiated from the pulse-induced electroporated leakage currents induced in the cell membranes. Under voltage clamp conditions, electroporated current as a percentage of the total transmembrane currents and the ratios of the membrane conductances responding to positive electrical pulses over negative electrical pulses have been quantified. These results imply that protein channels have a protective effect, mediating some of the changes to the phospholipid membrane from electroporation by adjusting the membrane conductance. Our hypothesis states that, when skeletal muscle fibers are exposed to a high intensity electrical field in real life, the increment in membrane conductance due to ion channels opening on the depolarized side of the cell membrane initiates a redistribution of the membrane potential differences across the two opposed membranes. The field-induced voltage drop across the membrane hemisphere facing the positive electrode is much higher than that across the hemisphere facing the negative electrode, which results in unequal electromediated permeabilization of the two hemispheres.