Interaction between Cations in Hydrophobic Solvent-Saturated Filters Containing Fixed Negative Charges

Ilani, Asher

doi:10.1016/s0006-3495(66)86660-2

Cited by 19 publications

(8 citation statements)

References 11 publications

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“…Some of the data presented above undoubtedly could be accounted for by a formal analogy with the analyses of several types of model charged membranes. In general, these are described by combining interracial forces which induce phase boundary potentials with a diffusional regime in a homogeneous charged membrane (6,24,33). The data presented above on the membrane of lobster muscle fibers, however, exhibit three varieties of complexity.…”

Section: Discussionmentioning

confidence: 99%

Permeability of Alkali Metal Cations in Lobster Muscle

Gainer

Grundfest

1968

The Journal of General Physiology

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Single muscle fibers from lobster walking legs are effectively impermeable to Na, but are permeable to K. They shrink in hyperosmotic NaCl; they swell in lo w NaCl media which are hyposmotic or which are made isosmotic with the addition of KC1. In conformity, the membrane potential is relatively insensitive to changes in external Na, while it responds according to the Nernst relation for changes in external K. When the medium is made isosmotic or hyperosmotic with RbC1 the volume and membrane potential changes are of essentially the same magnitudes as those in media enriched with KCI. The time courses for attaining equilibrium are slower, indicating that Rb is less permeant than K. Substitution of CsC1 for NaC1 (isosmotic condition) produces no change in volume of the muscle fiber. Addition of CsCl (hyperosmotic condition) causes a shrinkage which attains a steady state, as is the case in hyperosmotic NaC1. Osmotically, therefore, Cs appears to be no more permeant than is Na. However, the membrane depolarizes slowly in Ca-enriched media and eventually comes to behave as an ideal Ca electrode. Thus, the electrode properties of the lobster muscle fiber membrane may not depend upon the diffusional relations of the membrane and ions, and the osmotic permeability of the membrane for a given cation may not correspond with the electrophysiologically deduced permeability. Comparative data on the effects of Nt-14 and Li are also included and indicate several other degrees of complexity in the cell membrane. I N T R O D U C T I O NT h e idealized model to describe the resting potential of a cell (12,20,23) asserts that the potential is a function of the permeability of the various ions 399

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Section: Discussionmentioning

confidence: 99%

Permeability of Alkali Metal Cations in Lobster Muscle

Gainer

Grundfest

1968

The Journal of General Physiology

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“…It is noteworthy that the interaction between cations in the membranes of this study, is of reverse nature; the slow ion (Na) is slowed down by the appearance of Kin the membrane and vice versa (see Table IV). Possible mechanism for this kind of interaction are discussed elsewhere [6]. 3.…”

Section: Discussionmentioning

confidence: 99%

“…The activity coefficient of an ion in these membranes is undefined and thus, for instance, the potential change across one interface (equivalent to Donnan potential in ordinary ion exchangers) is also undefined. Yet the difference between two interfacial potentials and the diffusion potential can be evaluated by knowing the selectivity factor and the mobility of each ion as a function of membrane composition [10,6]. It is interesting to compare some of the properties of these membranes to those of the ordinary water filled ion exchange membranes.…”

Section: Discussionmentioning

confidence: 99%

“…additional diffusion potential across the membrane due to the higher mobility of K. This conclusion agrees qualitatively with the observed electrical conductivities of the membranes indicating that K is more mobile than Na and Li (Table II). A quantitative estimation of the diffusion potential is the K-Na bi-ionic cell is given by the author elsewhere [6].…”

Section: Bi-ionic Potentialmentioning

confidence: 99%

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Ion Exchange Membranes Saturated with Hydrophobic Solvents

Ilani

1966

Israel Journal of Chemistry

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Filters made of cellulose acetate and nitrate were saturated with toluene or bromobenzene and interposed between aqueous solutions. The membranes thus formed behaved like cation exchange membranes with the same capacity for both solvents. K ‐ Na bi‐ionic potential, its dependence on temperature, K ‐ Na selectivity and mobility ratio were similar in membranes saturated with the above solvents. However the absolute magnitude of the diffusibility was some 30 times lower in toluene saturated membranes. Activation energy of membrane conductance was higher by about 3800 cal/mole in the toluene saturated membrane. Electroosmotic phenomena in the membranes were negligible or nil. It is suggested that these membranes represent a prototype of ion exchange membranes, where the fixed charges with their counterions and hydration shell are embedded in hydrophobic medium.

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“…A low-cost volt-ohm meter capable of measuring resistances up to 40 M⍀ and voltages down to 0.1 mV (DMM-8020, Tecpel). 10. A Metex4650A/MetexM-3890D multimeter or equivalent with RS232 or USB connectivity.…”

Section: List Of Materialsmentioning

confidence: 99%

Ion permeability of artificial membranes evaluated by diffusion potential and electrical resistance measurements

Shlyonsky

2013

Advances in Physiology Education

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In the present article, a novel model of artificial membranes that provides efficient assistance in teaching the origins of diffusion potentials is proposed. These membranes are made of polycarbonate filters fixed to 12-mm plastic rings and then saturated with a mixture of creosol and n-decane. The electrical resistance and potential difference across these membranes can be easily measured using a low-cost volt-ohm meter and home-made Ag/AgCl electrodes. The advantage of the model is the lack of ionic selectivity of the membrane, which can be modified by the introduction of different ionophores to the organic liquid mixture. A membrane treated with the mixture containing valinomycin generates voltages from -53 to -25 mV in the presence of a 10-fold KCl gradient (in to out) and from -79 to -53 mV in the presence of a bi-ionic KCl/NaCl gradient (in to out). This latter bi-ionic gradient potential reverses to a value from +9 to +20 mV when monensin is present in the organic liquid mixture. Thus, the model can be build stepwise, i.e., all factors leading to the development of diffusion potentials can be introduced sequentially, helping students to understand the quantitative relationships of ionic gradients and differential membrane permeability in the generation of cell electrical signals.

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Interaction between Cations in Hydrophobic Solvent-Saturated Filters Containing Fixed Negative Charges

Cited by 19 publications

References 11 publications

Permeability of Alkali Metal Cations in Lobster Muscle

Permeability of Alkali Metal Cations in Lobster Muscle

Ion Exchange Membranes Saturated with Hydrophobic Solvents

Ion permeability of artificial membranes evaluated by diffusion potential and electrical resistance measurements

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