|Zhu, Yingting - IA STATE UNIV., AMES, IA|
Submitted to: American Society for Bone and Mineral Research
Publication Type: Abstract Only
Publication Acceptance Date: September 13, 1995
Publication Date: N/A
Technical Abstract: Calcium ATPases and calcium binding proteins are believed to play an important role in intestinal calcium transport. The calcium demands of pregnancy and lactation are known to up-regulate intestinal calcium absorption, but the mechanism is only partially known. In this study, intestinal calcium ATPase (PMCA1) and calcium binding protein (9K) mRNA levels were determined by Northern blotting at different stages of pregnancy and early lactation in rats. Intestinal calcium ATPase mRNA levels and calcium binding protein mRNA levels did not differ among non-pregnant rats and rats pregnant for 7 or 14 days. However, at 21 days gestation, both calcium ATPase mRNA and calcium binding protein levels increased 2- to 3-fold. Calcium ATPase and calcium binding protein levels remained elevated at 7 days of lactation. Plasma 1,25-dihydroxyvitamin D concentration exhibited a similar pattern, rising markedly at 21 days gestation and remaining elevated in lactation. These data suggest that the rise in 1,25-dihydroxyvitamin D stimulates transcription of calcium absorption factors in late gestation and early lactation.