The Formation and Properties of Thin Lipid Membranes from HK and LK Sheep Red Cell Lipids

Andreoli, Thomas E.; Bangham, Jenny; Tosteson, D. C.

doi:10.1085/jgp.50.6.1729

Cited by 89 publications

(100 citation statements)

References 30 publications

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“…When synthetic dioleoyllecithin was used instead of sheep red cell lipids to form bilayers, the observed V,, was lower. The molar ratio of cholesterol to phospholipids of lipids extracted from sheep red cells is about 1 (13) and cholesterol is known to decrease the fluidity of the hydrocarbon tails in bilayers as judged by ESR studies with spin labels (27,28). Thus, the result is consistent with the idea that the fluidity of the hydrocarbon interior is greater in dioleoyllecithin than in sheep red cell lipid membranes.…”

Section: J = "K(#'s -Ins) (4 B) J = K (-S -Os) (4 C)supporting

confidence: 75%

Effect of Peptide PV on the Ionic Permeability of Lipid Bilayer Membranes

Ting‐Beall

Tosteson

Gisin

et al. 1974

The Journal of General Physiology

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This paper reports the effects of peptide PV (primary structure:cyclo-(D-val-L-pro-L-val-D-pro)3) on the electrical properties of sheep red cell lipid bilayers. The membrane conductance (Gm) induced by PV in either Na+ or K+ medium is proportional to the concentration of PV in the aqueous phase. The PV concentration required to produce a comparable increase in Gm in K+ medium is about 104 times greater than for its analogue, valinomycin (val). Although the selectivity sequence for PV and val is similar, K + > Rb + > Cs + > NH4 > T1+ > Na + > Li+; the ratio of G, in K + to that in Na + is about 10 for PV compared to > 103 for val. When equal concentrations of PV are added to both sides of a bilayer, the membrane current approaches a maximum value independent of voltage when the membrane potential exceeds 100 mV. When PV is added to only one side of a bilayer separating identical salt solutions of either Na+ or K+ salts, rectification occurs such that the positive current flows more easily away rather than toward the side containing the carrier. Under these conditions, a large, stable, zero-current potential (Vm) is also observed, with the side containing PV being negative. The magnitude of this Vm is about 90 mV and relatively independent of PV concentration when the latter is larger than 2 X 10-6 M. From a model which assumes that Vm equals the equilibrium potential for the PV-cation complexes (MS+) and that the reaction between PV and cations is at equilibrium on the two membrane surfaces, we compute the permeability of the membrane to free PV to be about 10-6 cm s', which is about 10 -7 times the permeability of similar membranes to free val. This interpretation is supported by the fact that the observed values of Vm are in agreement with the calculated equilibrium potential for MS+ over a wide range of ratios of concentrations of total PV in the two bathing solutions, if the unstirred layers are taken into account in computing the MS+ concentrations at the membrane surfaces.

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Section: J = "K(#'s -Ins) (4 B) J = K (-S -Os) (4 C)supporting

confidence: 75%

Effect of Peptide PV on the Ionic Permeability of Lipid Bilayer Membranes

Ting‐Beall

Tosteson

Gisin

et al. 1974

The Journal of General Physiology

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“…The membrane potential was recorded as the potential difference between two calomel-KC1 electrodes which made contact with the front and rear solutions, as described by Andreoli, Bangham and Tosteson (1967).…”

Section: Methodsmentioning

confidence: 99%

“…Ion transference numbers were estimated from the zero-current potentials produced by imposing 5-to 10-fold ionic activity gradients across the membrane (see Andreoli et al, 1967). From the transference number (tj) and the total membrane conductance (G~), we estimated the conductive flux of the ion j by the equation:…”

Section: Methodsmentioning

confidence: 99%

Coupled transport of protons and anions through lipid bilayer membranes containing a long-chain secondary amine

Gutknecht

Walter

1979

J. Membrain Biol.

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Transport of protons and halide ions through planar lipid bilayers made from egg lecithin and a long-chain secondary amine (n-lauryl [trialkylmethyl] amine) in n-decane was studied. Net proton fluxes were measured with a pH electrode, and halide fluxes were measured with 82Br- and 36Cl-. In membranes containing the secondary amine, a large net proton flux was produced either by a Br- gradient with symmetrical pH or by a pH gradient with symmetrical Br-, but not by a pH gradient in Br--free solutions. This H+ flux was electrically silent (nonconductive), and the H+ permeability coefficient was greater than 10(-3) cm sec-1 in 0.1 M NaBr. In Br--free solutions, H+ selectivity was observed electrically by measuring conductances and zero-current potentials generated by H+ activity gradients. The permeability coefficient for this ionic (conductive) H+ flux was about 10(-5) cm sec-1, several orders of magnitude smaller than the H+ permeability of the electroneutral pathway. Large electroneutral Br- exchange fluxes occurred under symmetrical conditions, and the permeability coefficient for Br- exchange was about 10(-3) cm sec-1 at pH 5. The one-way Br- flux was inhibited by substituting SO4= for Br- on the "trans" side of the membrane. These results support a "titratable carrier" model in which the secondary amine exists in three forms (C, CH+ and CHBr). Protons can cross the membrane either as CHBr (nonconductive) or as CH+ (conductive), whereas Br- crosses the membrane primarily as CHBr (nonconductive). In addition to these three types of transport, there is also a pH-dependent conductive flux of Br- which has a permeability coefficient of about 10(-7) cm sec-1 at pH 5. Experiments with lipid monolayers suggest that the pH dependence of this conductive flux is caused by a change in surface potential of about +100 mV between pH 9.5 and 5.0.

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“…With the aim of determining the ionic selectivity (relative permeability of cations and anions) of these membranes, several investigators have measured the potentials exhibited by bilayers under an electrolyte gradient, and have applied the equation for diffusion potentials to calculate ionic transference numbers. A number of results indicate slight or no selectivity by membranes formed fromuncharged lipids (Mueller et al, 1962;Lev & Buzinsky, 1967;Andreoli, Bangham & Tosteson, 1967;Hopfer, Lehninger & Lenarz, 1970) and cation selectivity for membranes formed from negatively charged lipids Hopfer et al, 1970). Henn, on the other hand, found only slight cation selectivity in membranes formed from the negatively charged phosphatidyl serine (Henn & Thompson, 1969) while Miyamoto and Thompson (1961) observed a small degree of selectivity for cations in membranes formed from the neutral lipid phosphatidyl choline.…”

mentioning

confidence: 99%

Comparison of double layer potentials in lipid monolayers and lipid bilayer membranes

MacDonald

Bangham

1972

J. Membrain Biol.

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It is shown that the Gouy-Chapman double layer analysis adequately describes the variation of the surface potential of monolayers of acidic natural lipids over a wide range of surface charge density and salt concentration. It is also shown that the potential which initially appears when an electrolyte gradient is rapidly imposed across a bilayer membrane is due to a difference in the double layer potentials on the two sides of the membrane. This conclusion follows from the fact that the observed bilayer potentials arise much more rapidly than can be accounted for by charge migration across the membrane and from the observation that the bilayer membrane concentration potentials, when measured immediately after establishment of a gradient, are equal to the surface potential change observed when the subphase concentration of a monolayer of the same lipid is changed by an amount equal to the gradient across the bilayer. The bilayer potential and monolayer potential changes, so measured, agree in a number of different electrolyte solutions over a wide range of electrolyte concentrations and surface charge densities. Because of this agreement and the applicability of the Gouy theory to monolayers, initial bilayer potentials may be calculated if the composition of the mixture used to form the membrane is known, provided that the pK's and areas of such components are available. In the absence of this information, membrane potentials may be calculated from electrophoretic data on the membrane lipid mixture; the conditions under which the latter approach is possible have been determined. The experimental results indicate that the composition of monolyers and bilayers spread from the same lipid mixture in decane are very similar, that the composition of the two types of film closely resembles the composition of the solution used to generate them, and that bilayer membranes are close-packed. The evidence further indicates that if any hydrocarbon solvent remains in these bilayers, it must be so situated that it contributes little, if anything, to the surface area. The steady state potential in the bilayer membrane system is frequently not identical with the initial potential which supports the hypothesis that in many cases only a fraction of the electrical conductance of unmodified membranes is caused by the ions which constitute the bulk electrolyte. An expression for the relationship between diffusion and double layer potentials has been derived which shows that, in the absence of any intrinsic selectivity of the hydrocarbon region of the membrane for hydrogen, hydroxyl, or impurity, the two potentials should be identical.

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The Formation and Properties of Thin Lipid Membranes from HK and LK Sheep Red Cell Lipids

Cited by 89 publications

References 30 publications

Effect of Peptide PV on the Ionic Permeability of Lipid Bilayer Membranes

Effect of Peptide PV on the Ionic Permeability of Lipid Bilayer Membranes

Coupled transport of protons and anions through lipid bilayer membranes containing a long-chain secondary amine

Comparison of double layer potentials in lipid monolayers and lipid bilayer membranes

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