Sodium transfer in tortoise erythrocytes

Maizels, Montague

doi:10.1113/jphysiol.1956.sp005535

Cited by 29 publications

(18 citation statements)

References 20 publications

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“…cell water) than from Na contents (m-equiv/l. cells), but the relevant equation is complicated (see Maizels, 1956), and the figures for FCR are very similar whether it is calculated from this equation with Na expressed as a concentration, or from the equation given above, with Na expressed as a content. This is because cell water changes but little during incubation: thus even if cell volume altered by ± 5 %, cell water per unit volume would change by only ± 1-5 %.…”

Section: Resultsmentioning

confidence: 98%

Effect of sodium content on sodium efflux from human red cells suspended in sodium‐free media containing potassium, rubidium, caesium or lithium chloride

Maizels¹

1968

The Journal of Physiology

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SUMMARY1. Human red cells treated with lactose solution and loaded with NaCl and BCI subsequently exchange cation with a nutrient BCl medium. B is the same in cells and medium, and is either K, Rb, Cs or Li. In these circumstances Na always moves outwards with the concentration gradient, but the efflux is largely active.2. With suspensions in media containing Ca2 , the total Na efflux depends on the amount of Na in the cells and on the nature of cation B. Thus for any given value of mean cell Na (Nam) in excess of 30 m-equiv/l. cells, the effect of B on the amount of Na efflux is K > Cs > Rb > Li, while with Nam between 0 7 and 5 m-equiv/l. cells, the sequence is Cs > Li > K, Rb. With Nam between 5 and 30 m-equiv/l. cells, intermediate sequences may be demonstrated for the effects of B on Na efflux. This applies both to the efflux itself and to the flux: concentration ratio, FCR.3. FCR for passive Na efflux in these circumstances is determined by adding strophanthin G to the medium. It varies inversely with the duration of exposure to Ca2+ in the exchange and nutrient media, but not with the nature of cation B. FCR for passive efflux is probably little affected by the value of Nam.4. By deducting passive from total Na efflux, active Na efflux is obtained, and variations in the latter with cell Na content, and with B, result in FCR curves similar to those obtained with total Na efflux.5. Total and passive Na efflux have also been measured in Ca-free media. Here the passive efflux is considerable, and with Na + K cells in KCI media FCR increases with Nam, but in other systems this change is not signi-* In receipt of a personal grant from the Wellcome Trust, and a grant for equipment from the Public Health Service, U.S.A. (HE 08817-01) (National Heart Institute). ficant. However, the rate of passive efflux into LiCl media is less than that for KCO or CsCl media. Owing to the magnitude of passive flux in Ca-free systems, the total Na efflux is also increased, but FCR for active Na efflux is quantitatively and qualitatively similar to that occurring in systems containing Ca2+.6. The effects of B and Nanm on Na efflux give a series of sequences for B which recall some of those obtainable when chemically modified glass membranes separate solutions of salts, and which are attributable to the charge on the membrane and the hydration of the cations involved.

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Section: Resultsmentioning

confidence: 98%

Effect of sodium content on sodium efflux from human red cells suspended in sodium‐free media containing potassium, rubidium, caesium or lithium chloride

Maizels¹

1968

The Journal of Physiology

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“…Aebi (1950) has shown that Ca2+, but not Mg2+, delays the swelling of liver slices. In the case of the erythrocytes of the snapping turtle, Lyman (1945) has shown that haemolysis occurs when the cells are suspended in saline media unless Ca2+ is present; the same is true of tortoise erythrocytes (Maizels, 1956), the action of Ca2+ in each case being specific. Lyman's methods were not quantitative, but if the permeability of tortoise erythrocytes to radiosodium is measured, it may be shown that this increases greatly when the cells are suspended in Ca-free media, that salts of the heavy metals like Cd, Cu, etc., maintain or even lower permeability, but that this effect is due to coagulation of the cell membrane, and is accompanied by the death of the cell (Maizels, 1956).…”

Section: Discussionmentioning

confidence: 99%

Calcium ions and the permeability of human erythrocytes

Bolingbroke¹,

Maizels²

1959

The Journal of Physiology

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“…In the latter instance, however, there appeared to be a progressive increase in the rate coefficient for Na efflux as [Naji increased (Maizels, 1956). …”

Section: Easily Exchanged Cationmentioning

confidence: 99%

“…Traces of plasma trapped in this situation might contribute to the experimental error of replicates. This error would be minimized if, as in previous experiments (Maizels, 1956) centrifuging were interrupted at an early stage in order to resuspend and wash the cells in a tracer-free solution before completing the centrifuging. If the error were indeed due to trapping of traces of plasma, it would affect Na and Na* equally, and the error in Na -Na* should not be additive: in fact, this error at 7 and 22 hr is only + 0 1 m-equiv./l.…”

Section: Maizels and Mary Remingtonmentioning

confidence: 99%