A patch clamp study on the electro-permeabilization of higher plant cells: Supra-physiological voltages induce a high-conductance, K+ selective state of the plasma membrane

作者：Wegner Lars H^*; Flickinger Bianca; Eing Christian; Berghoefer Thomas; Hohenberger Petra; Frey Wolfgang; Nick Peter

来源：Biochimica et Biophysica Acta-Biomembranes, 2011, 1808(6): 1728-1736.

DOI：10.1016/j.bbamem.2011.01.016

• Electroporation
• Threshold potential
• Patch clamp
• Tobacco cell culture
• Bright yellow-2 (BY-2)

Permeabilization of biological membranes by pulsed electric fields ("electroporation") is frequently used as a tool in biotechnology. However, the electrical properties of cellular membranes at supra-physiological voltages are still a topic of intensive research efforts. Here, the patch clamp technique in the whole cell and the outside out configuration was employed to monitor current-voltage relations of protoplasts derived from the tobacco culture cell line "Bright yellow-2". Cells were exposed to a sequence of voltage pulses including supra-physiological voltages. A transition from a low-conductance (similar to 0.1 nS/pF) to a high-conductance state (similar to 5 nS/pF) was observed when the membrane was either hyperpolarized or depolarized beyond threshold values of around -250 to -300 mV and +200 to +250 mV, respectively. Current-voltage curves obtained with ramp protocols revealed that the electro-permeabilized membrane was 5-10 times more permeable to K+ than to gluconate. The K+ channel blocker tetraethylammonium (25 mM) did not affect currents elicited by 10 ms-pulses, suggesting that the electro-permeabilization was not caused by a non-physiological activation of K+ channels. Supra-physiological voltage pulses even reduced "regular" K+ channel activity, probably due to an increase of cytosolic Ca2+ that is known to inhibit outward-rectifying K+ channels in Bright yellow-2 cells. Our data are consistent with a reversible formation of aqueous membrane pores at supra-physiological voltages.

• 出版日期2011-6