Elementary [Ca2+]i signals generated by electroporation functionally mimic those evoked by hormonal stimulation

Bobanović, Fedja; Bootman, Martin D.; Berridge, Michael J.; Parkinson, Nicola A. and Lipp, Peter (1999). Elementary [Ca2+]i signals generated by electroporation functionally mimic those evoked by hormonal stimulation. FASEB journal : official publication of the Federation of American Societies for Experimental Biology, 13(2) pp. 365–376.

URL: http://www.fasebj.org/content/13/2/365.full.pdf+ht...


The generation of oscillations and global Ca2+ waves relies on the spatio-temporal recruitment of elementary Ca2+ signals, such as 'Ca2+ puffs'. Each elementary signal contributes a small amount of Ca2+ into the cytoplasm, progressively promoting neighboring Ca2+ release sites into an excitable state. Previous studies have indicated that increases in frequency or amplitude of such hormone-evoked elementary Ca2+ signals are necessary to initiate Ca2+ wave propagation. In the present study, an electroporation device was used to rapidly and reversibly permeabilize the plasma membrane of HeLa cells and to allow a limited influx of Ca2+. With low field intensities (100-500 V/cm), brief (50-100 μs) electroporation triggered localized Ca2+ signals that resembled hormone-evoked Ca2+ puffs, but not global signals. With such low intensity electroporative pulses, the Ca2+ influx component was usually undetectable, confirming that the electroporation-induced local signals represented Ca2+ puffs arising from the opening of intracellular Ca2+ release channels. Increasing either the frequency at which low-intensity electroporative pulses were applied, or the intensity of a single electroporative pulse (>500 V/cm), resulted in caffeine-sensitive regenerative Ca2+ waves. We suggest that Ca2+ puffs caused by electroporation functionally mimic hormone-evoked elementary events and can activate global Ca2+ signals if they provide a sufficient trigger.

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