Physiologically based models for bone-seeking elements. I. Rat skeletal and bone growth.

A review of features of bone structure and bone growth critical to the development of a physiologically based model of the whole-body kinetics of bone-seeking elements is presented. Allometric equations describing the volume and weight of the bone, bone marrow, and skeleton during growth of the rat from birth to maturity are derived. Weights of body calcium and bone ash are also expressed allometrically as functions of body weight during growth. The simplicity of these functions will allow them to form the basis of a flexible model of the movement of bone-seeking elements in and out of bone. Blood flow rates to bone and bone marrow are incorporated into the model of the mature skeleton. The predictions of the skeletal growth model are in good agreement with measured quantities of bone, skeletal ash, and calcium in growing rats.