Different Behavior of ⁴⁵Ca and ⁸⁹Sr in Chronic Uremia in the Rat

Abstract

In earlier experiments presented at the 8th Symposium (MEYER et al., 1971), we have investigated the different handling of ⁴⁵Ca and ⁸⁹Sr as tracers in a kinetic model of Calcium metabolism in the rat. We have shown highly significant higher excretion rates for Sr than for Ca in the urine (v_u) and the endogenous fecal secretion (v_f), which is in agreement with the literature (BAUER et al., 1955; COHN and GUSMANO, 1967; GREENBERG and TROESBER, 1942; PANY, 1967). Yet in contradiction to the findings of other workers, we have found a highly significant discrimination in favor of Ca for the bone accretion rate (v_o+). These results have raised the question whether the lower accretion of Sr was only the consequence of the faster urinary excretion, or if it was really an independent process.