The effects of stable strontium on calcium metabolism: I. Kinetic analysis of calcium metabolism in strontium-fed rats

Abstract

Stable strontium has been shown to inhibit the synthesis of 1α,25-dihydroxyvitamin D3(1,25(OH)2D3). In the present study, the effects of stable strontium on calcium metabolism were studied in growing rats. The rats were divided into control, 0.5%-Sr and 1.0%-Sr groups. After dietary treatment for 4 weeks, both intestinal calcium absorption (Vna) and the calcium absorption ratio (β) were suppressed dose-dependently by strontium. In contrast, while intestinal strontium absorption (sVna) was higher in the 1.0%-Sr group than that in the 0.5%-Sr group, there was no change in the strontium absorption ratio in the intestine (sβ). Although bone formation (Vo+) and bone resorption (Vo−) were both decreased in the strontium groups, no change was observed in the serum calcitonin and parathyroid hormone concentrations in the 1.0%-Sr group. Furthermore, a large amount of strontium deposited in newly formed bone. These results suggest that 1) the decrease of intestinal calcium absorption is due to either the reduction of 1,25(OH)2D3 synthesis or the competitive antagonistic action between calcium and strontium in the intestine, and 2) accumulation of a large amount of strontium in bone might directly inhibit bone formation and resorption.