Threshold Characterization of Ca2+ Uptake in CHO Cells Following 1-µs Electroporation Pulses

This experiment aimed to determine the threshold for calcium uptake in CHO cells subjected to 1-µs electric pulses. Cells were loaded with 2.5 µM Fluo-4, a Ca2+-sensitive dye, for 30 minutes in the dark. Fluo-4 fluorescence was excited using a FITC cube and a CoolLED illumination system. Time-lapse imaging was conducted at 1 frame per second for 5 minutes, with a single 1-µs pulse of varying amplitude applied 1 minute after the start of recording.