Role of kidney tissue in the production of 25-hydroxyvitamin D3-26,23-lactone and 1 alpha, 25-dihydroxyvitamin D3-26,23-lactone.
Labeled 25-hydroxyvitamin D3-26,23-lactone was isolated from the serum of vitamin D-repleted rats given [3 alpha-3H]-25-hydroxyvitamin D324 hr prior to sacrifice. The metabolite was identified by cochromatography with the authentic lactone on straight-phase and reversed-phase high-performance liquid chromatography. Production of the lactone was abolished by nephrectomy indicating that the kidney is the site of synthesis. Homogenate of kidneys from chickens given large doses of vitamin D can carry out in vitro production of the lactone from 25-hydroxyvitamin D3. When 1 alpha, 25-dihydroxyvitamin D3 was used as substrate, this system produced only traces of a compound believed to be 1 alpha, 25-dihydroxyvitamin D3-26,23-lactone. However, incubation of rachitic chicken kidney homogenates with 25-hydroxyvitamin D3-26,23-lactone produced substantial amounts of a compound that has been identified by mass spectrometry as 1 alpha, 25-dihydroxyvitamin D3-26,23-lactone. Thus, the development of a functional group on C-26 and eventual lactone formation takes place in kidney by a system acting on 25-hydroxyvitamin D3.
D000818:Animals; D002112:Calcifediol / Q000031:analogs & derivatives*; D002117:Calcitriol / Q000031:analogs & derivatives*; D002645:Chickens; D004100:Dihydroxycholecalciferols / Q000378:metabolism*; D006887:Hydroxycholecalciferols / Q000378:metabolism*; D007668:Kidney / Q000378:metabolism*; D007783:Lactones; D008297:Male; D051381:Rats
D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D007783:Lactones; C026396:calcifediol lactone; C026947:1,25-dihydroxyvitamin D3-26,23-lactone; D002117:Calcitriol; D002112:Calcifediol