The intestinal phosphate transport under condition of experimental hypercalcemia.

The analysis of the serum calcium and phosphate level changes in intact Vitamin D--dosed animals showed the increasing serum calcium values without any concomitant change in serum phosphate concentration. The observed discrepancy of intestinal phosphate transport in vitro and in vivo studies together with the effect of Vitamin D towards normalizing serum phosphate level in TPTX Vitamin D--dosed animals suggest the presence of Vitamin D as some phosphate regulatory factor. The participation of the possible role of 25 OH D3 in the observed phenomenon is under current investigations. In PTH supressed hypercalcemic conditions we did not reproduce, with the usage of 1alpha--OH D3, the regulatory effect of 1,25 (OH) 2D3 described by Garabedian et al. /1/.