Alkaline-Phosphatase Activity in Developing Molars of Vitamin D-deficient Rats. I. High Calcium-Phosphorus Ratio Diet

¹ Georgetown University Schools of Medicine and Dentistry, Department of Anatomy, Washington, D.C.

The role of alkaline phosphatase in the developing molars of the offspring of rats fed a rachitic diet was investigated. This diet has a calcium-phosphorus ratio of 4-5:1 and without vitamin D produces alterations similar to rickets. A supplement of vitamin D was added to a group of experimental animals to study the recovery process. Serial undecalcified sections of the jaws of experimental and control animals (birth-10 days) were stained with Gomori's cobalt technique for alkaline phosphatase. All developing molars in the rachitic group showed considerable decrease in alkaline-phosphatase activity as compared to controls. The reaction in the rachitic animals receiving therapeutic doses of vitamin D was almost similar to that of controls. The findings suggested that vitamin D may start a chain reaction first influencing upon alkaline-phosphatase activity. Alkaline phosphatase may influence mucopolysaccharide synthesis, which in turn may affect collagen formation. Primary alterations in the organic phase of calcifiable matrices may lead secondarily to defective mineralization. Whether vitamin D influences alkaline-phosphatase activity, and whether this enzyme plays a primary role in mucopolysaccharide synthesis and secondarily or indirectly affects fibrous protein formation and mineralization of calcifiable matrices, need further investigation.