Calcium Absorption in the'Rat in Relation to Excessive Vitamin D and Cortisone

Abstract

The effects of excessive amounts of vitamin D and/or cortisone on net Ca absorption determined in vivo, serum Calevels, intestinal active transport of Ca determined by an in vitro intestinal sac technic were investigated in the rat. Net Ca absorption was not increased by excessive vitamin D, nor decreased (actually increased) by concomitant cortisone or corticosterone administration. Active Ca transport studied in vitro was confined to the proximal small intestine, which was increased by excessive vitamin D and decreased by concomitant cortisone or corticosterone. Therefore, at least with the drugs, dosages, and time relationships used in this study, the in vitro intestinal sac technic is not considered a valid index of net calcium absorption in the intact animal.