Measurement of membrane potentials and test of theories

Lakshminarayanaiah, N.; Subrahmanyan, V.

doi:10.1002/pol.1964.100021018

Cited by 15 publications

(17 citation statements)

References 18 publications

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“…Following this, it is observed that X, the concentration of fixed charge, also changed, increasing gradually with increase in the external electrolyte concentration. It is gratifying to note that the equilibrium data given in Table 1 agree very well with the data derived a decade ago for the same membrane system (Lakshminarayanaiah & Subrahmanyan, 1964). In Table 2 are given the values for Era, the membrane potential, measured when the membrane separated NaC1 solutions of molality M1 and Mz.…”

Section: Resultsmentioning

confidence: 57%

“…Although the value of X as noted in this paper and elsewhere (Hills etal., 1961;Lakshminarayanaiah & Subrahmanyan, 1964) is concentration dependent, application of the TMS theory gives just one average value for X. Even the derivation of this value is beset with some difficulties which have been discussed by Lakshminarayanaiah (1966b).…”

Section: Discussionmentioning

confidence: 97%

“…Membrane potentials arising across the membrane separating solutions of concentration M1 and M2 were measured at 25 ~ using half-cells and procedures described in the earlier publications (Hills et al, 1961 ;Lakshminarayanaiah & Subrahmanyan, 1964). However, in the measurement of membrane potentials, anion reversible electrodes were not used directly in the solutions contacting the two membrane faces.…”

Section: Methodsmentioning

confidence: 99%

“…The membranes of phenolsulfonic acid cross-linked with formaldehyde (PSA membrane) were prepared according to the procedure given elsewhere (Lakshminarayanaiah & Subrahmanyan, 1964). They were washed thoroughly with deionized water and con-12" ditioned in 1 N HC1 solution.…”

Section: Methodsmentioning

confidence: 99%

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Measurement of membrane potential and estimation of effective fixed-charge density in membranes

Lakshminarayanaiah

1975

J. Membrain Biol.

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Electrical potentials Em arising across cross-linked phenolsulfonate membrane separating NaCl solutions of molality M1 and M2 have been measured at 25 degrees C. These values of Em have been used in the Nernst equation to calculate values for the apparent transport number ti(app) for the counterion or the co-ion in the membrane. Values of ti(app) together with the limiting value for the cation transport number in the aqueous phase have been used in the equation developed by Kobatake and co-workers to evaluate the membrane permselectivity Ps as a function of external electrolyte concentration. With the help of the equation relating Ps to phiX, the effective fixed-charge density in the membrane (where phi is a constant, 0 less than phi less than 1, and X is the membrane stochiometric charge density and can be evaluated by chemical analysis of the membrane phase), values for phiX and phi have been determined. Values of phi were low in dilute solutions and increased with increase in the concentration of the external solution. Similar behavior was noted in the case of another membrane system, cross-linked polymethacrylic acid in contact with KOH solutions. On the other hand, the membrane system, "untreated" collodion in contact with KCl solutions, exhibited a behavior in which the values of phi, low in dilute solutions, increased and then decreased following a gradual increase in the external concentration. This slight divergence in its behavior was attributed to the heterogeneity of the collodion membrane structure. The reliability of this potentiometric method to estimate effective fixed-charge density in membranes has been discussed in relation to a similar but old method due to Teorell, Meyer and Sievers. Also the significance of the values derived for phi has been pointed out.

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Section: Resultsmentioning

confidence: 57%

Section: Discussionmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Measurement of membrane potential and estimation of effective fixed-charge density in membranes

Lakshminarayanaiah

1975

J. Membrain Biol.

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“…Assumption (i) stated above is generally made by every investigator although it is commonly recognized that the most homogeneous membrane shows functionally characteristics that are typical of a heterogeneous membrane (Lakshminarayanaiah & Subrahmanyan, 1968). Assumptions (ii) and (iv) have been found to be quite drastic or rather unrealistic (Hills et aL, 1961 a, b;Lakshminarayanaiah, 1963;Lakshminarayanaiah & Subrahmanyan, 1964); whereas assumption (iii) has been shown to have little effect on the membrane parameters (Mackie &Meares, 1955;Boyd &Bunzl, 1967). Similarly, the contribution of factor (v) to membrane potential at ordinary concentrations is very small (Lakshminarayanaiah & Subrahmanyan, 1964).…”

Section: Discussionmentioning

confidence: 99%

Potentiometric estimation of charges in barnacle muscle fibers under internal perfusion

Lakshminarayanaiah

1974

J. Membrain Biol.

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Single barnacle muscle fibers from Megabalanus Psittacus (Darwin) were internally perfused with a number of solutions of K-acetate of concentration 6"2 which was increased from 100 to 600 mM maintaining a pH of 7.5. The external solutions at the same pH contained 40 mM MgAc 2 and K-acetate of concentration C1 which was varied from 10 through 60 mM. The tonicity of both internal and external fluids was maintained at 1,000 mosmole with sucrose. The membrane potential E m (the potential was referred to the external solution as ground) arising across the fiber membrane was measured using those internal and external solutions which maintained the ratio (C2/C1) at 10. Similar measurements but now maintaining the ratio (C2/C~) at 2, where C~ was the concentration of Tris-C1 in the internal perfusion fluid and was increased from 100 to 250 mM and C2 was the concentration of total C1 in the external fluid which contained 40 mM MgC12 and different amounts of Tris-C1 (120 to 420 raM), were also made using various isotonic solutions at pH 4.0. The measured values of E m corrected for the liquid junction potentials, on interpolation with the theoretical curves of E m plotted against log (1/C1) derived from the theory of membrane potential developed by Teorell and by Meyer and Sievers, gave values of 0.019 and 0.7 M for the density of fixed charges present on the membrane at pH 7.5 (cation selective) and 4.0 (anion selective), respectively. Also, values of 2.3 at pH 7.5 and 1.0 at pH 4.0 were derived for the mobility ratio of cation to anion.It is well recognized that charges present on the surface of biological membranes influence various aspects of biological behavior. A surface charge model has been used by Gilbert and Ehrenstein (1969) to explain some of the voltage-dependent characteristics of the conductance of the nerve fiber. Other biological phenomena, e.g. muscle contraction, protoplasmic streaming, etc., are likely to be greatly influenced by the nature of the charged membrane surfaces. Consequently, a number of techniques, mostly electrokinetic in nature, have been utilized by a number of investigators (see Gilbert, 1971 for a brief review) to estimate the density of charges present in membranes of various biological preparations. Recently,

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Light‐Powered Ion Pumping in a Cation‐Selective Conducting Polymer Membrane

Nie

Xiao

et al. 2022

Angewandte Chemie

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The simulation of the ion pumping against a proton gradient energized by light in photosynthesis is of significant importance for the energy conversion in a non-biological environment. Herein, we report lightpowered ion pumping in a polystyrene sulfonate anion (PSS) doped polypyrrole (PPy) conducting polymer membrane (PSS-PPy) with a symmetric geometry. This PSS-PPy conducting polymer membrane exhibits a cationic selectivity and a light-responsive surfacecharge-governed ion transport attributed to the negatively charged PSS groups. An asymmetric visible irradiation on one side of the PSS-PPy membrane induces a built-in electric field across the membrane due to the intrinsic photoelectronic property of PPy, which drives the cationic transport against the concentration gradient, demonstrating an ion-pumping effect. This work is a prototype that uses a geometry-symmetric conducting polymer membrane as a light-powered artificial ion pump for active ion transport, which exhibits potential applications in nanofluidic energy conversion.

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Measurement of membrane potentials and test of theories

Cited by 15 publications

References 18 publications

Measurement of membrane potential and estimation of effective fixed-charge density in membranes

Measurement of membrane potential and estimation of effective fixed-charge density in membranes

Potentiometric estimation of charges in barnacle muscle fibers under internal perfusion

Light‐Powered Ion Pumping in a Cation‐Selective Conducting Polymer Membrane

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