The effect of stable strontium on the alkaline phosphatase activity of rat tissues—in vitro studies

In vitro studies on the effect of various amounts (10^?6–10^?3 M) of stable strontium (Sr²⁺) on the alkaline and acid phosphatase activities of rat tissues have shown a diverse response of the enzymes depending on the Sr²⁺ level and the tissue. Although both the enzymes manifest reduced activities at 10^?3 M Sr²⁺ in almost all the tissues studied only those of liver alkaline phosphatase and small intestine acid phosphatase were significantly affected. There was, however, no change at lower Sr²⁺ concentrations. The Sr²⁺-induced apparent inhibition of liver alkaline phosphatase, was found to be nonspecific and reversible by the concomitant addition of magnesium probably due to the manifestation of the Mg²⁺-dependent enzyme. The implications of the inhibitory action of Sr have been discussed with reference to tissue Sr content regarding the possible therapeutic use of stable Sr for minimizing the retention of Sr-90.