Side chain metabolism of 25-hydroxy-[26,27-14C] vitamin D3 and 1,25-dihydroxy-[26,27-14C] vitamin D3 in vivo.
Radioactive CO2 was detected in expired air after the administration of 25-hydroxy-[26,27-14C] vitamin d3 to vitamin D-deficient hypocalcemic rats; 14co2 was also detected after the administration of 1,25-dihydroxy-[26,27-14C] vitamin D3 to rats raised on the same diet. Nephretcomy totally abolished 14CO2 formation after administration of 25-hydroxy-[26,27-14C] vitamin D3 but not after the administration of 1,25-dihydroxy-[26,27-14C] vitamin D3. The production of 14CO2 commenced within 4 hours after injection of 1,25-dihydroxy-[26,27-14C] vitamin D3, suggesting a possible relevance of this reaction to the function of 1,25-dihydroxyvitamin D3. These results at least demonstrate a new metabolic pathway of vitamin D3 metabolism involving the oxidation of a portion of the side chain of 1,25-dihydroxyvitamin D3 to CO2.
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism; D004100:Dihydroxycholecalciferols / Q000378:metabolism / Q000494:pharmacology; D006887:Hydroxycholecalciferols / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000378:metabolism; D008297:Male; D051381:Rats
D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D002118:Calcium