Mobility of Skeletal Phosphorus in a Mature Dairy Cow as Determined with Radioactive Phosphorus.

Abstract

P32 was used to measure the size of the "labile" P pool in the skeleton of a mature dairy cow ("labile" P includes the fraction of total bone P that rapidly exchanges with plasma inorganic P). About 1% of the total skeletal P is in this pool which represents a P store 15 times as large as the circulating inorganic P pool of the plasma. "Labile" P is distr. throughout the skeleton but is 3 times as concentrated in trabecular bone as it is in dense cortical bone. Autoradiograms of several bones show that labile P is deposited in discrete areas in cortical bone whereas the distr. is more uniform in trabecular bone.