[The effect of 1 alpha-OH-D3 on the process of fracture healing (author's transl)].

The purpose of this paper is to clarify the effect of 1 alpha-OH-D3 on the bone metabolism through fracture healing. Rats were fractured on the middle of femur and were given 1 alpha-OH-D3 every day. The relationship between biochemical and histological changes were studied through the process of fracture healing associated with remarkable remodeling. The results are summarized as follows: 1. As soon as serum Ca levels decreased temporarily after fracture, a increase of serum iP.T.H. levels occurred with the histological change such as a bone resorption. The secretion of P.T.H. is probably suppressed by 1 alpha-OH-D3 with subsequent increase of the resorption of bone tissue. 2. Following the increase of serum Ca levels, the decrease of serum iP.T.H. levels were observed, accompanied by the histological changes of bone formation. These changes were seen earlier in the 1 alpha-OH-D3 group than in the controlled group. 3. Bone formation in the 1 alpha-OH-D3 group could be seen at the same area at which the bone resorption had occurred before. 1 alpha-OH-D3 could promote osteocytic, osteoclastic osteolysis and also bone formation, activating basic multicellular units (B.M.U.). 4. Some difference was found in the uniting callus formation between 1 alpha-OH-D3 group and the controlled group. 5. In conclusion, administration of 1 alpha-OH-D3 during fracture healing is useful in stimulating direct callus formation from cortex.