Alkaline phosphatase and bone calcium parameters.

Effects of cadmium, an alkaline phosphatase inhibitor, on the calcium content of rat bone were investigated in vivo by a radioisotopic method. Disturbance of bone metabolism is observed in both the superficial (delta) and slow exchanges (Ve), which are also significantly decreased. The crystallized calcium bone compartment (E) is also strongly affected. It appears that changes in the superficial calcium exchanges cause the observed decrease in the crystallized calcium mass. The slowing of osteogenesis is confirmed by the decrease of serum alkaline phosphatase activity. A statistical examination of the correlation coefficient reveals a close link (P less than 0.01) between serum alkaline phosphatase activity and the influx of superficial calcium (Vo+) and, as a result, the crystallized bone calcium parameters. These results show that cadmium can be used to study the relationship between alkaline phosphatase and calcification. The present observations allow us to consider the possibility that alkaline phosphatase may play a role in determining the calcium content of the crystallized phases in deep bone through its action on the tissue surface.