Calcium 'homeostatic' effect of 1 alpha,25-dihydroxycholecalciferol on young adult mouse calvaria in organ culture.
The effect of 1 alpha,25-dihydroxycholecalciferol on calcium release from cultured young adult (75-day-old) mouse calvaria in the presence of indomethacin or dexamethasone was studied. Indomethacin (2.8 x 10(-7) M) or dexamethasone (10(-8) M) abolished or considerably inhibited basal calcium release. At 2.6 x 10(-7) M, 1 alpha,25-dihydroxycholecalciferol prevented the effect of either indomethacin or dexamethasone, resulting in higher calcium release levels approximating those observed in cultures containing only 1 alpha,25-dihydroxycholecalciferol. We have shown previously that in contrast to its effect on neonatal mouse calvaria in culture, 1 alpha,dihydroxycholecalciferol either failed to enhance or even inhibited basal calcium release from cultured 75-day-old mouse calvaria. Furthermore, 1 alpha,25-dihydroxycholecalciferol inhibited PTH- or PGE2-enhanced calcium release from such cultures. These studies demonstrated that, at the same concentration, 1 alpha,25-dihydroxycholecalciferol decreases high calcium release due to various bone resorption-stimulating factors and increases low calcium release values due to various bone resorption-inhibiting factors. This suggested that this vitamin D3 metabolite directly regulates the degree of bone resorption at the bone tissue level resulting in a local calcium 'homeostasis'.
Goldhaber
P
P
Harvard School of Dental Medicine, Boston, MA 02115.
Rabadjija
L
L
D000818:Animals; D001842:Bone and Bones / Q000187:drug effects* / Q000378:metabolism; D002117:Calcitriol / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D003907:Dexamethasone / Q000494:pharmacology; D006706:Homeostasis / Q000187:drug effects; D007213:Indomethacin / Q000494:pharmacology; D051379:Mice; D009924:Organ Culture Techniques
D003907:Dexamethasone; D002117:Calcitriol; D002118:Calcium; D007213:Indomethacin