Effect of X-Rays on Movements of Sodium in Human Erythrocytes

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Abstract
The effect of X-rays (890 rads to 8900 rads) on fluxes of sodium ions in human erythrocytes in vitro was investigated. The active and passive fluxes of sodium ions were differentiated by incubation of the cells in mediums containing or lacking potassium. In the absence of potassium in the external medium, the active efflux of sodium or sodium pump is abolished, without evident damage to the cell. The sodium pump is inhibited by X-irradiation. The dose-effect curve of the potassium-dependent sodium efflux can be analyzed by the following equation: P =p1e- [lambda]ld + p 2e-[lambda]2d where p 1 and p 2 are 2 components with different radiosensitivities; [lambda]1 and [lambda] 2 are the constants of in-activation by X-rays of p 1 and p 2; and d is the dose of X-rays, in rads. P2 is about 15 times as radioresistant as p1. The portion of sodium Afflux which occurs without potassium in the medium and the whole sodium influx are passive and are stimulated by X-irradiation. In both cases the increase is a linear function of the dose in the range 890 to 8900 rads, although the % rate of increase is different: 10.2 to 10.7 krad-1 for influx, and 6.3 krad-1 for passive efflux. This stimulation of passive fluxes may be due partly to increase in mobility of the hypothetical carriers for passive sodium transport in the membrane, and partly to discontinuation of membrane integrity and leakage of sodium.

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