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Nanosecond pulse stimulation and local E-field modeling. Nearly rectangular 600-ns pulses were generated in a transmission line-type circuit, by closing a MOSFET switch upon delivery of a TTL trigger pulse from pClamp software via a Digidata output. NsEP were delivered to a selected cell with a pair of tungsten rod electrodes (0.1-mm diameter, 0.16-mm gap). The position of pulser electrodes relative to the selected cell and patch-clamp recording pipette Alogliptin illustrated in Fig. 1 (inset). The exact pulse shapes and amplitudes were captured and measured with a 5-GHz TDS 3052 oscilloscope (Tektronix, Beaverton, OR). The E-field at the cell location between the electrodes was determined by 3D simulations with a finite element Maxwell equations solver Amaze 3D (Field Precision, Albuquerque, NM). In case of multiple nsEP exposures, the interval between stimuli was 0.5 or 1 s.
Results and discussion
We reported earlier that nsEP permeabilized plasma membrane similarly in GH3, Jurkat, and PC12 cells [13]. In this study, we compared the effect in GH3 cells, which express multiple types of endogenous ion channels [14] and CHO-K1 cells, which express very few channels [15]. In both cell lines, nsEP caused a characteristic long-lasting increase of the whole-cell conductance with profound rectification of the inward current. Although the extent of rectification varied, it was observed in most if not all nsEP-treated cells.