Failure of PTH, Calcitonin, or Vitamin D Metabolites to Influence Calcium Transport in the Maturation Stage Enamel Organ

¹ The Dental Research Center and The Department of Pedodontics, University of North Carolina, Chapel Hill, North Carolina 27514

Eleven-day-old rat maxillary first molar explants were removed by microdissection and incubatedin vitro to determine the direct effects of parathyroid hormone (PTH), calcitonin (CT), 1,25(OH)₂D₃, 24,25(OH)₂D₃, and a combination of PTH and vitamin D₃ metabolites on calcium uptake in the mineralizing enamel of the explants. None of the agents had a statistically significant effect. These results are in contrast to those observed on explants from six-day-old rats, where PTH + 24,25(OH)₂D₃ caused a significant increase in net calcium transport. The findings are consistent with the hypothesis that the transcellular transport of calcium through the secretory stage and the maturation stage ameloblasts occurs by different mechanisms.