Capacitive and ionic currents in BLM from phosphatidic acid in Ca2+-induced phase transition

Antonov, V. F.; Shevchenko, Elena V.; Kozhomkulov, E.T.; Molnar, A. A.; Smirnova, E. Yu.

doi:10.1016/0006-291x(85)91249-5

Cited by 16 publications

(20 citation statements)

References 5 publications

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“…Also the gel state exhibited some current fluctuations, which, however either slowly disappeared when waiting for extended times or led to membrane rupture (see supplementary data). Distinct quantized current fluctuations in lipid membranes have been reported before (2,(10)(11)(12)(13)(14)(15)(16)26,31) ranging between ~1 pA and ~1 nA close to the phase transition temperature.…”

Section: Permeability Changes During Lipid Membrane Phase Transitionmentioning

confidence: 82%

Phase-State Dependent Current Fluctuations in Pure Lipid Membranes

Wunderlich

Leirer

Idzko

et al. 2009

Biophysical Journal

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Current fluctuations in pure lipid membranes have been shown to occur under the influence of transmembrane electric fields (electroporation) as well as a result from structural rearrangements of the lipid bilayer during phase transition (soft perforation). We demonstrate that the ion permeability during lipid phase transition exhibits the same qualitative temperature dependence as the macroscopic heat capacity of a D15PC/DOPC vesicle suspension. Microscopic current fluctuations show distinct characteristics for each individual phase state. Although current fluctuations in the fluid phase show spikelike behavior of short timescales (approximately 2 ms) with a narrow amplitude distribution, the current fluctuations during lipid phase transition appear in distinct steps with timescales of approximately 20 ms. We propose a theoretical explanation for the origin of timescales and permeability based on a linear relationship between lipid membrane susceptibilities and relaxation times near the phase transition.

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Section: Permeability Changes During Lipid Membrane Phase Transitionmentioning

confidence: 82%

Phase-State Dependent Current Fluctuations in Pure Lipid Membranes

Wunderlich

Leirer

Idzko

et al. 2009

Biophysical Journal

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“…Gögelein & Koepsell [65] showed that channel events in brain phosphatidylserine can be "blocked" or inhibited by calcium ( Fig. 22, top, while Antonov et al [12] showed the reverse effect for DPPC membranes above the transition (Fig. 22, bottom).…”

Section: Figure 21mentioning

confidence: 99%

“…Bottom: Generation of quantized currents in DPPC membranes by calcium at T=64 • C (the melting temperature of DPPC is 41 • C). From [12]. a 'calcium-control' or 'calcium-gating' of the lipid channels.…”

Section: Figure 21mentioning

confidence: 99%

“…Interestingly, however, synthetic lipid membranes close to phase transitions are not inert but are very permeable for small molecules [2], ions [3,4,5,2] and water [6]. Further, they display stepwise conductance events very similar to those of proteins, i.e., with similar conductances and life times (some early publications: [7,8,9,10,11,12]). In their appearance, they are practically indistinguishable from recordings of protein-containing membranes.…”

Section: Introductionmentioning

confidence: 99%

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Lipid ion channels

Heimburg

2010

Biophysical Chemistry

148

178

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The interpretation of electrical phenomena in biomembranes is usually based on the assumption that the experimentally found discrete ion conduction events are due to a particular class of proteins called ion channels while the lipid membrane is considered being an inert electrical insulator. The particular protein structure is thought to be related to ion specificity, specific recognition of drugs by receptors and to macroscopic phenomena as nerve pulse propagation. However, lipid membranes in their chain melting regime are known to be highly permeable to ions, water and small molecules, and are therefore not always inert. In voltage-clamp experiments one finds quantized conduction events through protein-free membranes in their melting regime similar to or even undistinguishable from those attributed to proteins. This constitutes a conceptual problem for the interpretation of electrophysiological data obtained from biological membrane preparations. Here, we review the experimental evidence for lipid ion channels, their properties and the physical chemistry underlying their creation. We introduce into the thermodynamic theory of membrane fluctuations from which the lipid channels originate. Furthermore, we demonstrate how the appearance of lipid channels can be influenced by the alteration of the thermodynamic variables (e.g., temperature, pressure, tension and chemical potentials) in a coherent description that is free of parameters. This description leads to pores that display dwell times closely coupled to the fluctuation lifetime via the fluctuation-dissipation theorem. Drugs as anesthetics and neurotransmitters are shown to influence the channel likelihood and their lifetimes in a predictable manner. We also discuss the role of proteins in influencing the likelihood of lipid channel formation.

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“…This finding was first reported by Yafuso and collaborators (2) on oxidized cholesterol membranes. Numerous subsequent reports show that one finds channel-like events in synthetic lipid membranes in the complete absence of proteins (3)(4)(5)(6)(7)(8)(9)(10). The channels reported in those studies are typically of similar conductance (several 10 to 100 pS) and lifetime (a few ms to several 100 ms) than those of protein channels.…”

Section: Introductionmentioning

confidence: 97%

Voltage-Gated Lipid Ion Channels

Blicher

Heimburg

2013

PLoS ONE

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Synthetic lipid membranes can display channel-like ion conduction events even in the absence of proteins. We show here that these events are voltage-gated with a quadratic voltage dependence as expected from electrostatic theory of capacitors. To this end, we recorded channel traces and current histograms in patch-experiments on lipid membranes. We derived a theoretical current-voltage relationship for pores in lipid membranes that describes the experimental data very well when assuming an asymmetric membrane. We determined the equilibrium constant between closed and open state and the open probability as a function of voltage. The voltage-dependence of the lipid pores is found comparable to that of protein channels. Lifetime distributions of open and closed events indicate that the channel open distribution does not follow exponential statistics but rather power law behavior for long open times.

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Capacitive and ionic currents in BLM from phosphatidic acid in Ca2+-induced phase transition

Cited by 16 publications

References 5 publications

Phase-State Dependent Current Fluctuations in Pure Lipid Membranes

Phase-State Dependent Current Fluctuations in Pure Lipid Membranes

Lipid ion channels

Voltage-Gated Lipid Ion Channels

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