Phosphorus Metabolism in Resting and Pregnancy-stimulated Mammary Glands and in Spontaneous Mammary Carcinomas of Mice

Summary

1. Radioactive phosphorus, as Na₂HP³²O₄, was administered to normal and pregnant female mice and to females bearing mammary gland carcinomas, and the animals were sacrificed at 1, 4, 17, or 48 hours after injection. The mice were of the cancer-susceptible C3H and DBA strains. The amounts of phosphorus and radioactivity were determined in the acid-soluble, phospholipid, phosphoprotein, DNA, and PNA fractions.

2. The concentration of phosphorus in the DNA fraction of the carcinomas was increased threefold over that found in the resting glands, and twofold over that found in the stimulated glands. On the basis of the findings of other workers, it was concluded that this increased DNA phosphorus concentration denotes increased cellularity rather than increased nuclear concentration.

3. The concentration of phosphorus in the acid-soluble and PNA fractions of the mammary gland carcinomas more closely resembled that found in the pregnancy-stimulated glands, while that in the phospholipid and phosphoprotein fractions resembled that found in the resting glands.

4. The uptake of radioactivity in all fractions of the carcinomas, except the acid-soluble, was higher than in resting glands. In all fractions it was lower than in the physiologically stimulated glands.