The activities and concentrations of sodium and potassium in toad oocytes

Dick, D. A. T.; McLaughlin, Stuart

doi:10.1113/jphysiol.1969.sp008951

Cited by 61 publications

(32 citation statements)

References 21 publications

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“…The high C/N ratio is probably due to the fact that most (if not all) the nuclear Na exchanges with external Li, while only half the cytoplasmic Na exchanges with external Li. The C/N ratio obtained in the present experiments is higher than most of those obtained in previous studies on Li-exposed amphibian oocytes, which vary from 2.2 to 14.3, but confirms previous studies which indicated the presence of an internal cytoplasmic fraction of Na in the oocyte which is inexchangeable (or very slowly exchangeable) with external Li (7,9,10,12,14).…”

Section: Measurement On Oocytes (Bufo Bufo)contrasting

confidence: 55%

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Factors affecting the distribution of sodium and potassium in amphibian oocytes

Ibrahim

Dick

1984

Carlsberg Res. Commun.

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The concentrations of sodium, potassium and chloride in the nucleus and cytoplasm of amphibian oocytes were measured by electron microprobe X-ray analysis. It was confirmed that sequestered sodium, which is not or only slowly exchanged with external lithium, lies entirely in the cytoplasm, in either the cytoplasmic vesicles or yolk platelets, most probably in the vesicles. This vesicular sodium may be involved in cellular transport of sodium. Potassium is most concentrated in the nucleus and is retained by a mechanism not dependent on the sodium-potassium exchange pump, most probably by binding to protein.

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Section: Measurement On Oocytes (Bufo Bufo)contrasting

confidence: 55%

“…kinetic results (10 -30%) (12), (13 -62%) (8); autoradiographic results (22%) ( 10); and activity coefficient results (50%) (14).…”

Section: Measurement On Oocytes (Bufo Bufo)mentioning

confidence: 99%

Factors affecting the distribution of sodium and potassium in amphibian oocytes

Ibrahim

Dick

1984

Carlsberg Res. Commun.

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“…toad oocytes (Dick & McLaughlin, 1969) barnacle muscle (McLaughlin & Hinke, 1968), rabbit ventricle (Lee & Fozzard, 1975) and squid axon (Hinke, 1961). If the value for the total internal Na concentration of Purkinje fibres is 25 mm (Bosteels & Carmeliet, 1972a) and the value of internal Na activity found in the present experiments is used, then this ratio is 0-29.…”

Section: Discussionmentioning

confidence: 99%

The effects of external cations and ouabain on the intracellular sodium activity of sheep heart Purkinje fibres

Ellis¹

1977

The Journal of Physiology

313

219

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SUMMARY1. The intracellular Na activity of sheep heart Purkinje fibres has been measured using recessed-tip Na+-sensitive glass micro-electrodes.2. The internal Na activity was 7-2 + 2-0 mm (mean + S.D., n = 32) at the normal external Na concentration, [Na]0, in these experiments of 140 mm (equivalent to an external Na activity of 105 mM). The equilibrium potential for Na across the fibre membrane was therefore approximately + 70 mV. 4. The removal of external K produced an easily reversible increase in the internal Na with an initial rate equivalent to a concentration change of 0-24 + 0 07 m-mole/min (mean + S.D., n = 8).5. Ouabain produced increases in the internal Na activity that were only very slowly reversible. The threshold concentration for producing an increase was approximately 10-7 M. 10. The relationship between internal Na and contractility is discussed.

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“…The total element content of a cell can be divided operationally into freely diffusible and restricted fractions (Dick & McLaughlin, 1969):…”

Section: Microprobe Anal Ysis Of Cell Fluid Restricted Elements In Frmentioning

confidence: 99%

Diffusible sodium, potassium, magnesium, calcium and phosphorus in frog skeletal muscle.

Maughan¹,

Recchia²

1985

The Journal of Physiology

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SUMMARY1. A microvolumetric analytical method has been developed to measure the endogenous concentrations of diffusible elements in muscle cells.2. Single twitch fibres from frog muscle were skinned under oil and 0-2 nl drops of isosmotic sucrose solution, held in the tips of specially constructed pipettes, were placed in contact with the skinned fibres. After 0-10 min, the microdrops were removed and analysed with a wave-length dispersive X-ray spectrometer.3. The uptake of Na, K, Mg, and P into the microdrops was well fitted by a single exponential function, while the uptake of Ca was better represented by the sum of two exponential functions. All elements analysed except Ca reached diffusional equilibrium within 5 min of placing the microdrop on the fibre, while Ca was still not equilibrated at 10 min.4. For freshly isolated muscle fibres, diffusible element concentrations in the microdrops at equilibrium were (in mm, mean + S.D.): Na, 7-6 ± 72; K, 82 + 36; Mg, 5-8 + 30; P, 51+19. Diffusible Ca concentration (at 10 min elapsed sampling time) was 0-7+04 mM.5. Results from experiments in which microdrops were equilibrated with skinned fibres pre-soaked in an artificial (Ca-free) solution support the notion that the exogenous solutes can replace the endogenous diffusible contents of a skinned fibre by soaking the skinned fibre in a relatively large volume of the artificial solution.6. Total Na, K, Mg, Ca, and P content of whole muscle was measured by electron probe analysis of muscle extracts. In freshly isolated muscle, whole muscle element content was (in mmol/kg wet weight, mean + S.D.): Na, 21+8; K, 120+ 26; Mg, 9-7+2-6; Ca, 2-2+0-5; P, 76+ 18.

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The activities and concentrations of sodium and potassium in toad oocytes

Cited by 61 publications

References 21 publications

Factors affecting the distribution of sodium and potassium in amphibian oocytes

Factors affecting the distribution of sodium and potassium in amphibian oocytes

The effects of external cations and ouabain on the intracellular sodium activity of sheep heart Purkinje fibres

Diffusible sodium, potassium, magnesium, calcium and phosphorus in frog skeletal muscle.

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