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...

Abstract

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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About

• Item ORO ID
• 35035
• Item Type
• Journal Item
• ISSN
• 1530-6860
• Keywords
• Ca²+ puffs; Ca²+ waves; HeLa cells; confocal microscopy; InsP₃receptors
• Academic Unit or School
• Faculty of Science, Technology, Engineering and Mathematics (STEM) > Life, Health and Chemical Sciences
  Faculty of Science, Technology, Engineering and Mathematics (STEM)
• Copyright Holders
• © 1999 FASEB
• Depositing User
• Martin Bootman