Fetal rat bones in organ culture constitute a sensitive system for assay of the vitamin D metabolite, 1α, 25-dihydroxyvitamin D3. Significant bone resorption is obtained with as little as 2 pg 1, 25-dihydroxyvitamin D3 after 48 h of culture and with 1 pg after 64 h of culture. In the current study, organ cultures of fetal rat bone are used as a bioassay for 1, 25-dihydroxyvitamin D in normal human plasma, which was prepared for assay by extraction with dichloromethane, chromatography on Sephadex LH-20, and purification on silicic acid by high pressure liquid chromatography. The concentration of 1α, 25-dihydroxyvitamin D3 in normal adult human plasma was 24.8 ± 2.0 pg/ml (n = 19) by this assay.
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Clinical Biochemistry
- Biochemistry, medical