title: Gadolinium modifies the cell membrane to inhibit permeabilization by nanosecond electric pulses.
abstract: Lanthanide ions are the only known blockers of permeabilization by electric pulses of nanosecond duration (nsEP), but the underlying mechanisms are unknown. We employed timed applications of Gd(3+) before or after nsEP (600-ns, 20 kV/cm) to investigate the mechanism of inhibition, and measured the uptake of the membrane-impermeable YO-PRO-1 (YP) and propidium (Pr) dyes. Gd(3+) inhibited dye uptake in a concentration-dependent manner. The inhibition of Pr uptake was always about 2-fold stronger. Gd(3+) was effective when added after nsEP, as well as when it was present during nsEP exposure and removed afterward. Pores formed by nsEP in the presence of Gd(3+) remained quiescent unless Gd(3+) was promptly washed away. Such pores resealed (or shrunk) shortly after the wash despite the absence of Gd(3+). Finally, a brief (3s) Gd(3+) perfusion was equally potent at inhibiting dye uptake when performed either immediately before or after nsEP, or early before nsEP. The persistent protective effect of Gd(3+) even in its absence proves that inhibition by Gd(3+) does not result from simple pore obstruction. Instead, Gd(3+) causes lasting modification of the membrane, occurring promptly and irrespective of pore presence; it makes the membrane less prone to permeabilization and/or reduces the stability of electropores.
authors.affiliation: Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, 23508, USA. Electronic address: egianulis@odu.edu.
authors.forename: Elena C
authors.initials: EC
authors.lastname: Gianulis
authors.affiliation: Frank Reidy Research Center for Bioelectrics, Old Dominion University, Norfolk, VA, 23508, USA.
authors.forename: Andrei G
authors.initials: AG
authors.lastname: Pakhomov
mesh_terms: D000818:Animals; D016466:CHO Cells; D002412:Cations; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects; D004396:Coloring Agents / Q000737:chemistry; D006224:Cricetinae; D003412:Cricetulus; D004305:Dose-Response Relationship, Drug; D004563:Electrochemistry / Q000379:methods; D018274:Electroporation; D005456:Fluorescent Dyes / Q000737:chemistry; D005682:Gadolinium / Q000737:chemistry*; D036103:Nanotechnology / Q000379:methods*; D016062:Porosity
chemical_list: D002412:Cations; D004396:Coloring Agents; D005456:Fluorescent Dyes; D005682:Gadolinium
keywords: Electroporation; Gadolinium; Lanthanide ions; Nanosecond electric pulses