Publication: Impaired body calcium metabolism with low bone density and compensatory colonic calcium absorption in cecectomized rats
Issued Date
2012-04-01
Resource Type
ISSN
15221555
01931849
01931849
Other identifier(s)
2-s2.0-84859454623
Rights
Mahidol University
Rights Holder(s)
SCOPUS
Bibliographic Citation
American Journal of Physiology - Endocrinology and Metabolism. Vol.302, No.7 (2012)
Suggested Citation
Prapaporn Jongwattanapisan, Panan Suntornsaratoon, Kannikar Wongdee, Nitita Dorkkam, Nateetip Krishnamra, Narattaphol Charoenphandhu Impaired body calcium metabolism with low bone density and compensatory colonic calcium absorption in cecectomized rats. American Journal of Physiology - Endocrinology and Metabolism. Vol.302, No.7 (2012). doi:10.1152/ajpendo.00503.2011 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/13768
Research Projects
Organizational Units
Authors
Journal Issue
Thesis
Title
Impaired body calcium metabolism with low bone density and compensatory colonic calcium absorption in cecectomized rats
Other Contributor(s)
Abstract
An earlier study reported that ce-cal calcium absorption contributes less than 10% of total calcium absorbed by the intestine, although the cecum has the highest calcium transport rate compared with other intestinal segments. Thus, the physiological significance of th e cecum pertaining to body calcium metabolism remains elusive. Herein, a 4-wk calcium balance study in cecectomized rats revealed an increase in fecal calcium loss with marked decreases in fractional calcium absorption and urinary calcium excretion only in the early days post-operation, suggesting the presence of a compensatory mechanism to minimize intestinal calcium wasting. Further investigation in cecectomized rats showed that active calcium transport was enhanced in the proximal colon but not in the small intestine, whereas passive calcium transport along the whole intestine was unaltered. Since apical exposure to calcium-sensing receptor (CaSR) agonists similarly increased proximal colonic calcium transport, activation of apical CaSR in colonic epithelial cells could have been involved in this hyperabsorption. Calcium transporter genes, i.e., TRPV6 and calbindin-D 9k , were also upregulated in proximal colonic epithelial cells. Surprisingly, elevated serum parathyroid hormone levels and hyperphosphatemia were evident in cecectomized rats despite normal plasma calcium levels, suggesting that colonic compensation alone might be insufficient to maintain normocalcemia. Thus, massive bone loss occurred in both cortical and trabecular sites, including lumbar vertebrae, femora, and tibiae. The presence of compensatory colonic calcium hyperabsorption with pervasive osteopenia in cecectomized rats therefore corroborates that the cecum is extremely crucial for body calcium homeostasis. © 2012 the American Physiological Society.