Identification and determination of 25-hydroxyvitamin D3 in the blood and liver of vitamin D-deficient rats irradiated with ultraviolet light.

The intestinal calcium transport activity and serum calcium and phosphorous concentrations of vitamin D-deficient rats were increased by irradiation with an ultraviolet (UV) lamp. The existence of 25-hydroxyvitamin D3(25-OH-D3) in their bloods and livers was physicochemically confirmed by high-performance liquid chromatography (HPLC), gas-liquid chromatography (GLC) and mass fragmentography, whereas the compound could not be detected in the tissues of non-irradiated rats. The results strongly suggested that vitamin D3 in vivo generated in irradiated rat skin might be normally metabolized and utilized to prevent rickets. The level of 25-OH-D3 in the tissues was determined by a HPLC method.