Effects of depot medroxyprogesterone acetate on the calcium metabolism of adult ovariectomized rats

This paper describes experiments designed to test the effect of depot medro xyprogesterone acetate (DMPA) on calcium metabolism of adult ovariectomized rats. The 24 animals were randomly assigned to control or treated groups. Treated rats received 15 mg of DMPA i.m. per week, during four or twelve we eks. Controls received solvent alone. The variables characterizing the meta bolism of Ca (daily rates of intestinal absorption and excretion, bone accr etion and resorption and the sizes of the exchangeable pools and their rate constants) were measured with the aid of Ca-45 according to Aubert and Mil haud. No effects were observed at four weeks of treatment. After twelve wee ks, treatment produced serum levels of 46.5 +/- 5.6 nmoles of medroxyproges terone/L, reduction of bone turnover (Ca accretion and resorption rates) an d of the size of the stow exchanging Ca compartment. The increase in true C a intestinal absorption was compensated by the increased endogenous fecal C a excretion. The mass of body Ca was not affected by treatment.