1. Tumour cells were starved to deplete them of ATP and transferred to 0·9mm-glycine in Ringer solutions containing 2mm-sodium cyanide and various Na+ and K+ concentrations. The uptake of glycine then usually reached a peak by about 10min. 2. When cellular [Na+] and extracellular [Na+] were each about 30m-equiv./l., the maximum amount of glycine absorbed increased between 1·2- and 3·0-fold on lowering extracellular [K+] from 128 to 10m-equiv./l. 3. When extracellular [Na+] was 150m-equiv./l., the ratio, R, of the cellular to extracellular glycine concentrations increased progressively, from near 1 to about 9, when cellular [Na+] was lowered from 120 to 40m-equiv./l. 4. When cellular [Na+] was almost constant, either at 45 or 70m-equiv./l., R fell about 14-fold when extracellular [Na+] varied from 150 to 16m-equiv./l. 5. Values of R near 0·2 were found when cellular [Na+] was about four times as large as extracellular [Na+]. 6. R fell about threefold when the cells were put with 12mm- instead of 0·9mm-glycine. 7. The results were taken to imply that, under these conditions, the spontaneous movements of both Na+ and K+ across the cell membrane, down their respective concentration gradients, served to concentrate the glycine in the tumour cells (Christensen's hypothesis).
The effects of varying the cellular and extracellular concentrations of sodium and potassium ions on the uptake of glycine by mouse ascites-tumour cells in the presence and absence of sodium cyanide
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A A Eddy; The effects of varying the cellular and extracellular concentrations of sodium and potassium ions on the uptake of glycine by mouse ascites-tumour cells in the presence and absence of sodium cyanide. Biochem J 1 July 1968; 108 (3): 489–498. doi: https://doi.org/10.1042/bj1080489
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