Calmodulin may mediate 1,25-dihydroxyvitamin D-stimulated intestinal calcium transport.

1,25-Dihydroxyvitamin D (1,25(OH)2D stimulated an increase in calmodulin content in chick duodenal brush border membranes in parallel with an increase in duodenal calcium transport in vivo and calcium uptake by brush border membrane vesicles (BBMV) in vitro. The increase in calcium uptake by BBMV was blocked by specific calmodulin antagonists. These results suggest that calmodulin mediates 1,25(OH)2D-stimulated calcium movement across the brush border membrane.