Elektrophysiologische Phänomene

Ümrath, Karl

doi:10.1007/978-3-642-94676-9_37

Cited by 2 publications

(2 citation statements)

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“…Two other marine algae, Halicystis and Porphyra, show cytoplasmic potentials of SO and -42 mv, respectively (Blount and Levedahl, 1960; R. W. Eppley, personal communication). In fresh-water algae and higher plants the plasmalemma potentials are usually somewhat larger (Walker, 1955;Umrath, 1956;Findlay and Hope, 1964;Spanswick and Williams, 1964). Finally, the outward transport of Na + , possibly coupled with an inward transport of K + , occurs at the outer plasma membrane of many plant and animal cells (see Dainty, 1962Dainty, , 1964.…”

Section: C M Cmentioning

confidence: 99%

Sodium, Potassium, and Chloride Transport and Membrane Potentials in Valonia Ventricosa

Gutknecht¹

1966

The Biological Bulletin

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Section: C M Cmentioning

confidence: 99%

Sodium, Potassium, and Chloride Transport and Membrane Potentials in Valonia Ventricosa

Gutknecht¹

1966

The Biological Bulletin

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“…The giant cells of Nitellopsis obtusa, a brackish water, ecorficate, characean seemed the most suitable cells available to work with. Much previous work has been done on members of this group, particularly by Collander, Osterhout, Blinks, Umrath, andothers (Collander (1936, 1939); reviews by Osterhout (1955), Blinks (1955), Umrath (1956)). However, these studies have been confined chiefly to chemical measurements of normal concentrations in cell sap and the net uptake from unfamiliar media under a variety of conditions, and electrical measurements of potentials and resistances.…”

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confidence: 99%

Ion Transport in Nitellopsis Obtusa

Macrobbie

Dainty

1958

The Journal of General Physiology

171

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The distribution and rates of exchange of the ions sodium, potassium, and chloride in single internodal cells of the ecorticate characean, Nitdlopsis obtusa, have been studied.In tracer experiments three kinetic compartments were found, the outermost "free space" of the cell, a compartment we have called "protoplasmic non4ree space", and the cell sap.The concentrations in the vacuole were 54 m~ Na +, 113 mM K +, and 206 m~ C1-. The steady state fluxes across the vacuolar membrane were 0.4 pmole Na+/cm. ~ sec., 0.25 pmole K+/cm. s sec., and 0.5 pmole C1-/cm? sec.The protoplasmic Na/K ratio is equal to that in the vacuole but protoplasmic chloride is relatively much lower. Osmotic considerations suggest a layer 4 to 6 # thick with sodium and potassium concentrations close to those in the vacuole. The fluxes between protoplasm and external solution were of the order of 8 pmoles Na+/ cm. ~ sec. and 4 pmoles K+/cm. 2 sec.We suggest that the protoplasm is separated from the cell wall by an outer protoplasmic membrane at which an outward sodium transport maintains the high K/Na ratio of the cell interior, and from the vacuole by the tonoplast at which an inward chloride transport maintains the high vacuolar chloride. The tonoplast appears to be the site of the principal diffusion resistance of the cell, but the outer protoplasmic membrane probably of the main part of the potential. I N T R O D U C T I O NThere are practically no studies on the ion permeability of plant ceils and tissues which are comparable--in the details elucidated--with those made by animal physiologists on nerve, muscle, and erythrocytes. The plant cell with its cell wall, large central vacuole, and thin layer of protoplasm is sufficiently complicated to make such a study difficult but in the plant physiologists' favourite material--roots, storage tissue, etc.--these difficulties are added to by morphological complications. It has thus been possible less often in plant systems to express the results of an experiment in fully quantitative terms--as an ion flux in pmoles (10 -12 moles) per sq. cm. per second across a well defined morphological boundary separating two phases in which the electrochemical activities of the ion are known. This is the general aim of our work. 335

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Elektrophysiologische Phänomene

Cited by 2 publications

References 74 publications

Sodium, Potassium, and Chloride Transport and Membrane Potentials in Valonia Ventricosa

Sodium, Potassium, and Chloride Transport and Membrane Potentials in Valonia Ventricosa

Ion Transport in Nitellopsis Obtusa

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