TY - JOUR
T1 - Enterohepatic physiology of 1,25-dihydroxyvitamin D3
AU - Kumar, R.
AU - Nagubandi, S.
AU - Mattox, V. R.
AU - Londowski, J. M.
PY - 1980
Y1 - 1980
N2 - After intravenous administration of radiolabeled 1,25-dihyroxyvitamin D3 to rats, ~25% of the administered radioactivity appeared in the bile within 24 h. Instillation of the biliary radioactivity into the duodena of other rats was followed by recovery of 15% of the radioactivity in newly secreted bile within 24 h. The process by which products of 1,25-dihydroxyvitamin D3 were excreted in bile was not saturable in the dose range tested (0.275-650 ng). The metabolites of 1,25-dihydroxyvitamin D3 present in bile were found to be much more polar than 1,25-dihydroxyvitamin D3 and were resolved into three fractions on high performance liquid chromatography. 60% of the radioactivity present in bile was retained selectively by DEAE-cellulose; the radioactive material could be eluted from the gel at a low pH or at high salt concentrations. When bile containing the radiolabeled metabolites was incubated at 37°C and pH 5 with β-glucuronidase, there was an increase in the amount of radioactivity comigrating with 1,25-dihydroxyvitamin D3. Treatment of the products of radiolabeled 1,25-dihydroxyvitamin D3 in bile with diazomethane, an agent which converts acids into methyl esters, transformed one of the metabolites into a less polar compound. These results demonstrate that there is a quantitatively important enterohepatic circulation of the products of 1,25-dihydroxyvitamin D3 in the rat.
AB - After intravenous administration of radiolabeled 1,25-dihyroxyvitamin D3 to rats, ~25% of the administered radioactivity appeared in the bile within 24 h. Instillation of the biliary radioactivity into the duodena of other rats was followed by recovery of 15% of the radioactivity in newly secreted bile within 24 h. The process by which products of 1,25-dihydroxyvitamin D3 were excreted in bile was not saturable in the dose range tested (0.275-650 ng). The metabolites of 1,25-dihydroxyvitamin D3 present in bile were found to be much more polar than 1,25-dihydroxyvitamin D3 and were resolved into three fractions on high performance liquid chromatography. 60% of the radioactivity present in bile was retained selectively by DEAE-cellulose; the radioactive material could be eluted from the gel at a low pH or at high salt concentrations. When bile containing the radiolabeled metabolites was incubated at 37°C and pH 5 with β-glucuronidase, there was an increase in the amount of radioactivity comigrating with 1,25-dihydroxyvitamin D3. Treatment of the products of radiolabeled 1,25-dihydroxyvitamin D3 in bile with diazomethane, an agent which converts acids into methyl esters, transformed one of the metabolites into a less polar compound. These results demonstrate that there is a quantitatively important enterohepatic circulation of the products of 1,25-dihydroxyvitamin D3 in the rat.
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U2 - 10.1172/JCI109669
DO - 10.1172/JCI109669
M3 - Article
C2 - 7356679
AN - SCOPUS:0018834168
SN - 0021-9738
VL - 65
SP - 277
EP - 284
JO - Journal of Clinical Investigation
JF - Journal of Clinical Investigation
IS - 2
ER -