Visualization of Plasma Membrane Potential Changes Within Nanoseconds Time Intervals Using Strobe Fluorescence
Speaker Biographical Sketch
Iurii Semenov received an M.S. (1996) and Ph.D. (2002) degrees in biophysics at Taras Shevchenko Kyiv National University in Ukraine. He is Research Assistant Professor at Frank Reidy Research Center for Bioelectrics. His current research interests are focused on intracellular effects of nanosecond pulsed electric fields, molecular mechanisms of intracellular calcium regulation, and signal-transduction pathways in the excitable and non-excitable cells.
2021 Frank Reidy Research Center for Bioelectrics Retreat
A growing number of applications involving exposure to ultrashort electric pulses demand a better understanding of plasma membrane (PM) charging dynamics while subjected to nanosecond pulsed electric field (nsPEF) exposure. Accurate measurements of cell PM changes would verify fundamental hypotheses describing the degree of voltage change across a PM and cellular sensitivity to the applied electric field of ultrashort duration.
We utilized a newly developed strobe fluorescence microscopy system and voltage-sensitive dye FluoVolt to measure changes in PM potential with a temporal resolution of +/- 25 ns. This approach allowed us to visualize a recently postulated megahertz compression phenomenon. Megahertz compression is the ability of nsPEF to accumulate charge on the PM if the interpulse time interval in a train is shorter than PM discharge time. Here we demonstrate how PM potential changes at cathode and anode sides of a CHO cell subjected to trains of 200 ns pulses applied with intervals of 200 ns or 400 ns (Fig 1).
Also, we show dynamics of PM potential changes in the CHO cells stimulated by electrodes arrayed in a quadrupole. 600 ns or 200 ns pulses were applied in the way to create bipolar cancellation for inhibition of nsPEF effects near the electrodes but promote distant stimulation in the center of the array. Our data show that in the cells situated between the electrodes at the periphery of the array, plasma membrane’s short depolarizations and hyperpolarizations follow a bipolar electric field created by electrical switching of the anode. However, in the center of the array, where the cancellation of cancellation (CAN-CAN) effect is achieved, the cell’s PM potential follows re-created monopolar electric pulse. The strobe fluorescence microscopy system presents a new powerful tool to push forward our understanding of the interactions of nsPEF with biological systems.
Semenov, Iurii; Silkunas, Mantas; and Pakhomov, Andrei G., "Visualization of Plasma Membrane Potential Changes Within Nanoseconds Time Intervals Using Strobe Fluorescence" (2021). 2021 Frank Reidy Research Center for Bioelectrics Retreat. 2.
0000-0002-0302-1355 (Semenov); 0000-0003-3816-3860 (Pakhomov)