[Metabolism of 3H-25-oxycholecalciferol in rats with experimental fracture of the femur].

At the third day after femur fracture concentration of 3H-25-hydroxycholecalciferol [3H-25(OH)D3], intraperitoneally administered into rats within 18 hrs before killing, was increased in kidney and small intestine mucosa by 25% and 60%, respectively, as well as incorporation of the label into 1,25(OH)2D3 in blood serum and small intestine mucosa was increased by 50% and 70%, respectively, as compared with intact controls. Binding of 3H-25(OH)D3 was increased 2-3-fold in diaphyses and epiphyses of impaired bones within 3 and 10 days after the fracture. Similar, but less distinct accumulation of 3H-25(OH)D3 was observed in unimpaired femur of rats with the bone fracture. Incorporation of the label into 1,25(OH)2D3 and 24,25(OH)2D3 was increased 1.5-2-fold in epiphyses of the impaired bone as well as in epiphyses and diaphyses of intact femur of rats with the bone fracture at all the periods studied (3, 10, 28 days after the fracture).