Influence of lanthanum on calcium transport and retention in the rat duodenum.

The present study examined the effects of lanthanum on calcium retention and transport in rat duodenal segments in vitro. Increasing the concentration of lanthanum from 0.1 to 10 mM in both the serosal and mucosal media produced a progressive decrease in tissue calcium retention and calcium transport. The addition of 10 mM lanthanum to the mucosal media alone reduced both calcium retention and transport. The addition of 10 mM lanthanum to the serosal media alone decreased calcium transport but did not alter total calcium retention by the duodenal segments. The results of this study indicate that lanthanum at a concentration of 1--10 mM acts at calcium transport sites in rat duodenum to reduce both calcium uptake and extrusion, with the net result that the addition of lanthanum to either the mucosal media, serosal media or both significantly reduced calcium transport.