Bone matrix studies. Influences of parathyroid extract, calcitonin, and cholecalciferol and of rickets and its treatment.

Bones from young rats were incubated with radioactive glucosamine and proline. The concentrations and specific activities of matrix glycosaminoglycan fractions, prepared by a cetylpyridinium chloride method, and the specific activity of insoluble collagen hydroxyproline were determined. Acute parathyroid extract treatment increased labelling of hyaluronic acid and a glycopeptide fraction. These effects were partially blocked by calcitonin treatment which had no effect by itself. Parathyroid extract inhibited collagen synthesis and this effect was not blocked by calcitonin. Effects of these two hormones on labelling of chondroitin sulfate fractions were more variable. Vitamin D-3 caused an increase in labelling of all matrix fractions measured in bone from thyroparathyroidectomized rats, but its stimulating effect upon collagen synthesis was blocked by parathyroid extract. Bones from rats made rachitic on a phosphorus and vitamin D-deficient diet were incubated in vitro with radioactive glucosamine and proline. Over a three-week period rachitic bone exhibited a progressive fall in concentration and labelling of a glycopeptide-hyaluronic acid fraction, while pair-fed animals supplemented either with phosphorus alone or with phosphorus and vitamin D-3 not only remineralized their bones, but the bones showed a pronounced increment in concentration and labelling of this fraction. Both treatment regimens also enhanced chondroitin sulfate and collagen labelling.