Correlation between alkaline and acid phosphatase activities and age-related osteopenia in murine vertebrae

Lumbar vertebrae (L4) from CW-1 female mice were examined for age-related changes in alkaline and acid phosphatase activities from young to old age. Histochemically, both enzymes were encountered along the bony surfaces of both trabecular and cortical bones with no significant age-related changes in their distribution. Biochemical determinations of bone alkaline phosphatase (Alk'ase) activity revealed that for a given unit level of bone or the bone as a whole no significant changes took place, whereas acid phosphatase (Acid'ase) activity was found to have increased significantly with age. A high positive correlative relationship was noted between the calcium content and the trabecular bone volume of the same vertebrae. It may, therefore, be proposed that age-related bone loss in mice could be attributed to an enhanced resorption rather than to a substantial reduction in the formative potential of bone cells.