Evidence for Extra-Renal 1 α-Hydroxylation of 25-Hydroxyvitamin D 3 in Pregnancy
1979; American Association for the Advancement of Science; Volume: 204; Issue: 4399 Linguagem: Inglês
10.1126/science.451538
ISSN1095-9203
AutoresT K Gray, Gayle E. Lester, R Lorenc,
Tópico(s)Electrolyte and hormonal disorders
ResumoThe kidneys are thought to be the only organs capable of 1 α-hydroxylation of vitamin D and its metabolites. We have examined the in vivo conversion of 3 H-(25,26)-25-hydroxyvitamin D 3 (25OHD 3 ) to 3 H-(25,26)-1 α,25-dihydroxyvitamin D 3 [1α,25(OH) 2 D 3 ] in vitamin D-deficient, pregnant and nonpregnant rats. As expected, nephrectomy of nonpregnant, vitamin D-deficient rats prevented the conversion of 25OHD 3 to 1α,25(OH) 2 D 3 . In contrast, nephrectomy of pregnant, vitamin D-deficient rats reduced but did not abolish the formation of 1 α,25(OH) 2 D 3 from its precursor. The identity of the radioactive metabolite formed from 3 H-25OHD 3 which circulated in nephrectomized, pregnant rats was established as 1α,25(OH) 2 D 3 by comigration with synthetic 1 α,25(OH) 2 D 3 on high-pressure liquid chromatography. The simultaneous absence of 1 α,25(OH) 2 D 3 in the fetal kidneys indicated that the site of 1 α-hydroxylation after nephrectomy of the pregnant rat was probably extra-renal in origin. Two sites of 1 α-hydroxylation of 25OHD 3 , one renal and the other extra-renal, either fetoplacental or maternal, may exist in the pregnant, vitamin D-deficient rat.
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