Reports

Side chain metabolism of 25-hydroxy-[26,27-14C] vitamin D3 and 1,25-dihydroxy-[26,27-14C] vitamin D3 in vivo

Science  06 Aug 1976:
Vol. 193, Issue 4252, pp. 493-494
DOI: 10.1126/science.941020

Abstract

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.

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