Aufnahme und Abgabe von Calcium an Erythrocyten vom Menschen

Rummel, W.; Seifen, Ernst; Baldauf, J.

doi:10.1007/bf00738223

Cited by 14 publications

(9 citation statements)

References 13 publications

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“…In the present experiments the [Ca] in the cell water of fresh human red cells was found to be approximately 0-06 mm, whereas Rummel et al (1962) found 0* 14 m-mole-Ca/l. cells.…”

Section: Discussioncontrasting

confidence: 66%

“…Passow (1961Passow ( , 1963 reported that Ca introduced into substrate-depleted cells was not extruded upon addition of adenosine or inosine and concluded that the Ca gradient observed in normal cells was due to an impermeable membrane. Rummel et al (1962) and Passow (1961Passow ( , 1963 found a remarkably small uptake of Ca from solutions of physiological Ca concentration.…”

Section: Discussionmentioning

confidence: 99%

“…Some insight into the passive permeability of the red cell membrane to Ca has been gained. From the studies of Passow (1961Passow ( , 1963 and Rummel, Seifen & Baldauf (1962), it is apparent that Ca penetrates the intact membrane with extreme difficulty. A measurable uptake of Ca into the cell was noticed only in substrate-depleted cells at Ca concentrations above 4 mM, or in normal cells exposed to isotonic Ca solution in the cold.…”

mentioning

confidence: 99%

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Calcium movements across the membrane of human red cells

Schatzmann¹,

Vincenzi²

1969

The Journal of Physiology

518

159

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SUMMARY1. A study has been made of the cellular content and movement of Ca across the membrane of human red blood cells.2. The [Ca] in the cellular contents of fresh red cells is 4 09 x 10-2 mM.The intracellular concentration of free ionic Ca ([Ca2+]) is considered to be less than this value and therefore less than extracellular [Ca2+] under normal conditions.3. Observation of unidirectional Ca fluxes with 45Ca confirms previous reports of low permeability of the red cell membrane for Ca. After nearly 1 week of loading in the cold, intracellular 45Ca content is 1-8 % of extracellular 45Ca content. Appearance in extracellular fluid of 45Ca from coldloaded cells can be considered to arise from two compartments. Efflux of 45Ca from the 'slower compartment' is accelerated by the addition of glucose.4. Starved red cells, incubated at 370 C, after reversible haemolysis for loading with Ca and Mg-ATP, exhibit an outward net transport of Ca against an electrochemical gradient. The transport is associated with the appearance of inorganic phosphate (PI). Cells treated similarly, but without ATP show no transport and no appearance of Pi.5. During the initial phase of transport, 1 3 mole Pi appear per mole Ca transported. 6. The transport of Ca from ATP-loaded cells is highly temperaturedependent, with a Q10 of 3.5.7. Cell membrane adenosine triphosphatase (ATPase) activity of reversibly haemolysed cells is stimulated only by intracellular, and not by extracellular Ca.8. Neither Ca transport in reversibly haemolysed cells, nor the Ca-Mg activated ATPase of isolated cell membranes is sensitive to Na, K, ouabain or oligomycin.

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“…In the present experiments the [Ca] in the cell water of fresh human red cells was found to be approximately 0-06 mm, whereas Rummel et al (1962) found 0* 14 m-mole-Ca/l. cells.…”

Section: Discussioncontrasting

confidence: 66%

Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Calcium movements across the membrane of human red cells

Schatzmann¹,

Vincenzi²

1969

The Journal of Physiology

518

159

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“…The values of the k's of passive 45Ca efflux from human erythrocyte ghosts observed in the present experiments are higher than anticipated from previous measurements of 45Ca permeability of intact erythrocytes (Rummel et al, 1962;Passow, 1963;Schatzmann & Vincenzi, 1969). In an attempt to load intact erythrocytes with Ca, Schatzmann and Vincenzi (1969) found that the cells took up only very small quantities of 45Ca during cold storage for periods up to 6 days.…”

Section: Discussioncontrasting

confidence: 64%

Calcium efflux from human erythrocyte ghosts

Porzig

1970

J. Membrain Biol.

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The passive Ca efflux from human red cell ghosts was studied in media of differing ion compositions and compared to the ATP-dependent Ca efflux. Cells were loaded with(45)Ca during reversible hemolysis, and the loss of radioactivity into the non-radioactive incubation medium was measured, usually for 3 hr at 37°C. Analysis of the efflux curves revealed that(45)Ca efflux followed the kinetics of a simple two-compartment system. In the concentration range between 0 and 1MM Ca in the external solution ([Ca(++)] o ), the rate constant of passive Ca efflux (k min(-1), fraction of(45)Ca lost per minute into the medium) increased from 0.00732 to 0.0150 min(-1). There was no further increase at higher [Ca(++)] o . The relation between the rate constant of Ca efflux and [Ca(++)] o is thus characterized by saturation kinetics. The passive transfer system for Ca could also be activated by Sr. The alkali metal ions Na, K and Li did not seem to have any significant influence on passive Ca transfer. The passive Ca efflux was slightly inhibited by Mg and strongly inhibited by Pb. Under most experimental conditions, a fraction of 15 to 50% of the intracellular Ca seemed to be "inexchangeable". The inexchangeable fraction decreased with increasing [Ca(++)] o and increased with increasing [Ca(++)] i . It was not influenced by alkali metal ions, CN or Pb, but it could be completely removed from the cells by the addition of 0.1MM Mersalyl to the incubation medium or by hemolysis with addition of a detergent. The active ATP-dependent Ca transport differed characteristically from passive transfer; the rate constant decreased with increasing [Ca(++)] o , and the inexchangeable Ca fraction increased with increasing [Ca(++)] o . The experimental results suggest that there exists a carrier-mediated Ca-Ca exchange diffusion in the erythrocyte membrane and that only a fraction of the ghost cell population participates in the Ca exchange diffusion.

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“…It is important in this context that starved red cells, although comparable to OCa-ghosts with respect to their cellular Ca content (cf. Harrison & Long, 1968, own control measurements in connection with the present work), seemed to lack type "A" binding sites, since they did not take up any appreciable amount of Ca under comparable conditions (Rummel, Seifen & Baldauf, 1962;Long &Mouat, 1971; this paper, see p. 15). These observations suggest that type "A" binding sites are not accessible or do not exist under physiological conditions but are made available during the conversion of red cells into ghosts and by the concomitant changes in membrane structure.…”

Section: Discussionmentioning

confidence: 82%

ATP-independent calcium net movements in human red cell ghosts

Porzig

1972

J. Membrain Biol.

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Aufnahme und Abgabe von Calcium an Erythrocyten vom Menschen

Cited by 14 publications

References 13 publications

Calcium movements across the membrane of human red cells

Calcium movements across the membrane of human red cells

Calcium efflux from human erythrocyte ghosts

ATP-independent calcium net movements in human red cell ghosts

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