Studies on the skeletal tissues. 4. The renewal of inorganic phosphate in bones of various species of small mammal as a function of time

Abstract

The rate of tracer uptake in long bones varies according to species; the incorporation of P32 is considerably slower in the cat than in the rabbit or rat. No decrease of tracer concentration occurs in the cortical parts of the long bones of the rabbit, cat or rat, or in the cancellous parts of the two former species in the course of 30 days. The decrease of the specific activity of P in the cancellous bones of the rat is explained by the continued skeletal growth of this animal in adult age. The species differences are much better shown with a newly developed technique which affords an almost complete separation of the newly labeled bone salts from old-established bone. Large differences were found in the function of various parts of the shaft. The different aspects of bone renewal in the adult animal, such as initial uptake, recrystallization, Haversian replacement, mobilization of fixed isotopes, equilibrium between bone and blood minerals, are discussed in the light of the new observations.