Makin G, Lohnes D, Byford V, Ray R, Jones G
Department of Biochemistry, Queen's University, Kingston, Ontario, Canada.
Biochem J. 1989 Aug 15;262(1):173-80. doi: 10.1042/bj2620173.
1,25-dihydroxyvitamin D3 is converted to calcitroic acid before being excreted in the bile. Biosynthesis of calcitroic acid has been demonstrated in two target cells of vitamin D, in the kidney and the osteoblastic cell line UMR-106. Calcitroic acid was identified by combinations of h.p.l.c., u.v. spectroscopy and mass spectrometry. Evidence is presented that calcitroate is derived from the 24-oxidation pathway, possibly through the intermediate 24,25,26,27-tetranor-1,23-dihydroxyvitamin D3. The 24-oxidation pathway to calcitroic acid in bone cells is stimulated by 1,25-dihydroxyvitamin D3. The pathway in both bone cells and perfused kidney operates at physiological concentrations of substrate and appears to be capable of rapid clearance of the hormone.
1,25-二羟基维生素D3在经胆汁排泄之前会转化为钙三醇酸。在维生素D的两个靶细胞(肾脏和成骨细胞系UMR-106)中已证实了钙三醇酸的生物合成。通过高效液相色谱、紫外光谱和质谱联用鉴定出了钙三醇酸。有证据表明,钙三醇酸盐源自24-氧化途径,可能是通过中间产物24,25,26,27-四降-1,23-二羟基维生素D3。骨细胞中通向钙三醇酸的24-氧化途径受1,25-二羟基维生素D3刺激。骨细胞和灌注肾脏中的该途径在底物的生理浓度下起作用,并且似乎能够快速清除该激素。