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

Abstract

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.

FIG. 1

Disappearance curve for ⁸⁵Sr from arterial blood sampled at 1-min intervals.

FIG. 2

Effect of La³⁺ on blood flow (upper) and mineral deposition (lower). Test side was right tibia; control side was left.

FIG. 3

Effect of KCN on blood flow (upper) and mineral deposition (lower). Correlation coefficient, r, for log deposition ratio versus dose is −0.53 (P < 0.005). For log flow ratio versus dose, r = −0.62 (P < 0.001).