title: Synthesis of (1,2- 3 H 2 )cholecalciferol and metabolism of (4- 14 C,1,2- 3 H 2 )- and (4- 14 C,1- 3 H)-cholecalciferol in rachitic rats and chicks.
abstract: [1,2-(3)H(2)]Cholecalciferol has been synthesized with a specific radioactivity of 508mCi/mmol by using tristriphenylphosphinerhodium chloride, the homogeneous hydrogen catalyst. With doses of 125ng (5i.u.) of [4-(14)C,1-(3)H(2)]cholecalciferol the tissue distribution in rachitic rats of cholecalciferol and its metabolites (25-hydroxycholecalciferol and peak P material) was similar to that found in chicken with 500ng doses of the double-labelled vitamin. The only exceptions were rat kidney, with a very high concentration of vitamin D, and rat blood, with a higher proportion of peak P material, containing a substance formed from vitamin D with the loss of hydrogen from C-1. Substance P formed from [4-(14)C,1,2-(3)H(2)]cholecalciferol retained 36% of (3)H, the amount expected from its distribution between C-1 and C-2, the (3)H at C-1 being lost. 25-Hydroxycholecalciferol does not seem to have any specific intracellular localization within the intestine of rachitic chicks. The (3)H-deficient substance P was present in the intestine and bone 1h after a dose of vitamin D and 30min after 25-hydroxycholecalciferol. There was very little 25-hydroxycholecalciferol in intestine at any time-interval, but bone and blood continued to take it up over the 8h experimental period. It is suggested that the intestinal (3)H-deficient substance P originates from outside this tissue. The polar metabolite found in blood and which has retained its (3)H at C-1 is not a precursor of the intestinal (3)H-deficient substance P.
mesh_terms: D000818:Animals; D001842:Bone and Bones / Q000032:analysis; D002247:Carbon Isotopes; D002645:Chickens; D002762:Cholecalciferol / Q000032:analysis / Q000096:biosynthesis* / Q000097:blood / Q000378:metabolism*; D002849:Chromatography, Gas; D004247:DNA / Q000032:analysis; D007668:Kidney / Q000032:analysis; D011506:Proteins / Q000032:analysis; D011874:Radiometry; D051381:Rats; D012279:Rickets / Q000378:metabolism*; D013997:Time Factors; D014316:Tritium; D014808:Vitamin D Deficiency / Q000378:metabolism
chemical_list: D002247:Carbon Isotopes; D011506:Proteins; D014316:Tritium; D002762:Cholecalciferol; D004247:DNA