[Effects of the dihydroxyl metabolites of vitamin D3 and their ethanol solvent on parathyroid secretion: in vivo study in the rat].

The regulation of parathyroid secretion by the vitamin D3 dihydroxylated metabolites was studied by differents authors. In vitro experiments showed that 1 alpha (OH)2 D3 and 24 R 25 (OH)2 D3 inhibited the PTH release. In Rats maintained in a normal calcium diet or calcium and/or vitamin D deficient diet, 1 alpha 25(OH)2 D3 and 24 R 25 (OH)2 D3 inhibited the PTH release, whereas 24 S 25 (OH)2 D3, 25 S 26 and 25 R 26(OH)2 D3 had no effect.

Intracellular localization of calcitonin in the C cells of the rat.

Specific localization of C cells at the electron microscope level was achieved by an indirect immunoperoxidase technique. The hormone is present in the electron dense granules. The presence of granules apparently devoid of calcitonin was also detected.