The phosphorus-containing constituents of various tissues of the rat were separated into five fractions. These were: inorganic and organic phosphorus soluble in aqueous 10% trichloroacetic acid; phosphorus soluble in 3:1 alcohol–ether; phosphorus derived from ribonucleic acid; and phosphorus derived from thymonucleic acid. In order to test the methods, inorganic phosphate, disodium phenyl phosphate, and purified ribonucleic and thymonucleic acids were added to a homogenate of rat liver in 10% trichloroacetic acid. It was possible by separation and analysis of the fractions to obtain a quantitative recovery of the added phosphorus in the appropriate fractions. The extent to which radioactive inorganic phosphate entered the other fractions was measured following its addition to a homogenate of rat liver in 10% trichloroacetic acid. When the fractionation was performed at room temperature it was found that all of the fractions except the organic acid-soluble phosphorus fraction contained negligible amounts of the added radioactive phosphorus. The amount of radioactive phosphorus taken up by this fraction could be reduced to a negligible quantity by working quickly and with cold solutions.Data are given showing the radioactive and nonradioactive phosphorus contents of the various fractions of liver, spleen, kidney, muscle, thymus gland, lymph node, prostate gland, and testis of the rat 24 hr. after the intraperitoneal injection of a solution of radioactive inorganic phosphate. By analysis of the urine, feces, and remainder of the rat after removal of the above tissues, a quantitative account was made of the injected radioactive phosphate.
A simplified method for the determination of circulating red‐cell volume with radioactive phosphorus