Regulation of intracellular calcium concentration by nanosecond pulsed electric fields

Changes in Ca²⁺]_i response of individual Jurkat cells to nanosecond pulsed electric fields (nsPEFs) of 60 ns and field strengths of 25, 50, and 100 kV/cm were investigated. The magnitude of the nsPEF-induced rise in Ca²⁺]_i was dependent on the electric field strength. With 25 and 50 kV/cm, the Ca²⁺]_i response was due to the release of Ca²⁺ from intracellular stores and occurred in less than 18 ms. With 100 kV/cm, the increase in Ca²⁺]_i was due to both internal release and to influx across the plasma membrane. Spontaneous changes in Ca²⁺]_i exhibited a more gradual increase over several seconds. The initial, pulse-induced Ca²⁺]_i response initiates at the poles of the cell with respect to electrode placement and co-localizes with the endoplasmic reticulum. The results suggest that nsPEFs target both the plasma membrane and subcellular membranes and that one of the mechanisms for Ca²⁺ release may be due to nanopore formation in the endoplasmic reticulum.