Multiple conductance states of lipid pores during Voltage-Clamp electroporation

Abstract

We used voltage-clamp electroporation to obtain single-channel recordings of lipid pores and analyzed the idealized dwell-time sequences using Maximum-Likelihood Fitting. We observed traces with multiple current levels and determined whether they were a result of the presence of multiple pores or a single pore with multiple conductance states. We found that, within the same recording, the bilayer can have a single pore with multiple conductance states or multiple independent pores. Using high sampling rates (100 kHz) we were able to observe pores with 40 μs lifetimes, and in experiments using high-voltage pulses we observed the existence of long-lived fluctuations minutes after the removal of the electric field. These results come closer to reconciling the nanosecond lifetime pores in molecular dynamics simulations and the long-lived permeability of cells after electroporation.

Keywords: Electroporation; Ion-channel Kinetics; Maximum-Likelihood Fitting; Model Selection; Voltage-Clamp.