EFFECTS OF PROPRANOLOL ON BONE METABOLISM IN THE RAT

Propranolol, a nonspecific beta-blocker, has many physiologic effects. Its effects on bone in vivo are unknown, although beta-receptor sites have been found on osteoblasts. In this study, the hypothesis tested was that low doses of propranolol could alter bone properties and enhance orthotopic endochondral bone formation. In a group of nonsurgical rats, propranolol treatment increased femoral torsional strength on biomechanical testing. In the rat surgical model used, right femora were fixed to a polyethylene plate and then defects were created mid-diaphysis and subsequently filled with demineralized bone matrix. These rats (defect rats) were randomly divided into groups that were given propranolol or a saline carrier for 19 consecutive days. In the defect rats, increased trabecular femoral metaphyseal mineral apposition rates were observed in propranolol-treated groups. Densitometry and roentgenographic scoring of callus formation after 12 weeks in propranolol-treated rats revealed increased callus and bone union. The results of this study indicate that propranolol treatment can significantly affect bone properties.