Effect of pamidronate on bone blood flow in oophorectomized rats

In connection with the known inhibitive action of bisphosphonates on bone resorption we were interested in their possible influence on bone blood flow (BBF). We determined BBF (85Sr-microsphere uptake in the tibia, distal femur and diaphysis of femur), cardiac output, density and ash weight of the tibia, as well as 24-h incorporation of 45Ca and 3H-proline into the tibia. Pamidronate (Aredia, CIBA-Geigy, Switzerland) was administered to sham-operated or oophorectomized (OOX) female rats in doses of 0.6 mg i.p. 2 days a week for 4 weeks. 85Sr-microsphere uptake was increased after OOX in the tibia and distal femur, simultaneous pamidronate administration significantly suppressed this increase below the control level. In addition, pamidronate inhibited the 24-h incorporation of 45Ca and 3H-proline in sham-operated females and suppressed the incorporation of 3H-proline that was increased after OOX. Bone density and ash weight were significantly increased after pamidronate administration in both sham-operated and OOX rats. The results of both experiments showing a significant effect of pamidronate on BBF and incorporation of 45Ca and 3H-proline require further verification and elucidation.