Free mammalian cells have been immersed in various bathing fluids to ascertain the effects on intracellular amino acid concentration and incorporation.

A large divergent metabolic effect has been found between normal and malignant cells when incubated in a well buffered hypertonic solution containing large amounts of sucrose, potassium, and magnesium (Medium A). The use of Medium A almost inhibited protein synthesis in thymus cells while allowing excellent incorporation in ascites tumor cells. This and Medium C even lessened the usual depression in tumor cells produced by the presence of the detergent Sterox CD.

Medium B, composed of 175 mm sucrose, 60 mm potassium, 4 mm magnesium with a bicarbonate buffer, allowed protein synthesis in the Ehrlich hyperdiploid ascites cells similar to that obtained in buffered Tyrode solution, but there was a marked decrease in the ability of these ascites cells to concentrate glycine.

A deleterious effect of potassium upon incorporation by thymus cells has been shown even in isotonic solutions.

Magnesium added to Tyrode solution #1 had no effect upon protein synthesis by thymus or ascites cells when incubated either with or without added detergent.

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This investigation was supported by a grant (No. C 2867) from the National Cancer Institute, National Institutes of Health, United States Public Health Service; and by a grant from the Massachusetts Division, American Cancer Society.

This is Publication #1023 of the Cancer Commission of Harvard University.

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