Inhibition of transport of 47Ca and 85Sr by lanthanum in canine cortical bone.

Deposition of 85Sr and 47Ca and blood flow (measured by iodoantipyrine washout) were determined in the tibial cortex of adult dogs after injection of graded doses of lanthanum chloride (LaCl3) and potassium cyanide (KCN) into the right tibial nutrient artery. Deposition of 85Sr and 47Ca, expressed in milliliters per gram of cortical bone in 10 min, was decreased after injections of lanthanum, 0.045 ± 0.008 (mean ± SE) compared to 0.097 ± 0.01 in control experiments (P < 0.005). Blood flow was unchanged. Injection of KCN did not affect the mean value of uptake of mineral (0.108 ± 0.01 vs. 0.097 ± 0.01) over the whole range of KCN dosage. Blood flow tended to be slightly higher with lower doses of KCN. These data support the concept of a transport system in bone for bone-seeking isotopes such as 85Sr and 47Ca.