Radioreceptor Assay for 1α,25-Dihydroxyvitamin D
            <sub>3</sub>

Brumbaugh, P. F.; Haussler, David; Bressler, Rubin; Haussler, Mark R.

doi:10.1126/science.183.4129.1089

Cited by 222 publications

(89 citation statements)

References 22 publications

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“…Some vitamin D may also be associated with the cellular and chylomicron fractions of whole blood. Another protein, in addition to Gc-VDBG, may be involved in the transport of la,25-dihydroxy-vitamin D3, the hormonal form of the vitamin which occurs in very low concentrations (9,22). These observations notwithstanding, the evidence strongly supports the contention that Gc-VDBG plays a primary role in vitamin D transport in vivo.…”

Section: Discussionsupporting

confidence: 61%

Group-specific component (Gc) proteins bind vitamin D and 25-hydroxyvitamin D.

Daiger¹,

Schanfield²,

Cavalli-Sforza³

1975

Proc. Natl. Acad. Sci. U.S.A.

350

162

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Section: Discussionsupporting

confidence: 61%

Group-specific component (Gc) proteins bind vitamin D and 25-hydroxyvitamin D.

Daiger¹,

Schanfield²,

Cavalli-Sforza³

1975

Proc. Natl. Acad. Sci. U.S.A.

350

162

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“…This is about 0.1% of the amount of radioactivity actually present in each intact rat plasma or intestinal sample (4100,000 dpm; see Fig. 1 (7)(8)(9)(10)(11)(12). It should also be kept in mind that both laboratories involved in the Lambert et aL study (6) previously reported plasma 1,25(OH)2D3 levels to be undetectable in anephric subjects (10,12 (6) should be interpreted cautiously because of the points raised above and because of contrary evidence from groups using diverse techniques (2-5, 7-12, 27).…”

Section: Gray Et Al (5) Administeredmentioning

confidence: 99%

“…The authors concluded that 1,25(OH)2D3 was present in the plasma of anephric subjects. However, other investigators, using radioreceptor, radioimmune, and biological assays for 1,25(OH)2D3, have been unable to detect 1,25(OH)2D3 in anephric persons (7)(8)(9)(10)(11)(12).…”

mentioning

confidence: 99%

Do tissues other than the kidney produce 1,25-dihydroxyvitamin D3 in vivo? A reexamination.

Shultz¹,

Fox²,

Heath³

et al. 1983

Proc. Natl. Acad. Sci. U.S.A.

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Recent experiments have shown that 1,25-dihydroxyvitamin D3-like material is produced in cultured nonrenal cells and may be present in the sera of anephric patients. We reexamined the question of whether 1,25-dihydroxyvitamin D3 can be synthesized extrarenally in the rat in vivo. To intact, sham-operated, ureter-ligated, or acutely nephrectomized vitamin D-deficient rats raised on a diet normal in calcium and phosphorus, we gave a physiologic dose of high-specific-activity 25-hydroxy-[3H]vitaminD3(3.6-3.81uCi; -25pmolper rat). Twenty-fourhours later we examined their tissues and plasma for the presence of radiolabeled 1,25-dihydroxyvitamin D3. Large amounts of radioactivity that behaved chromatographically as identical with authentic 1,25-dihydroxyvitamin D3 were present in the plasma, bone, and intestine of the intact, sham-operated, or ureter-ligated rats. However, no radioactivity eluting in a manner similar to 1,25-dihydroxyvitamin D3 was found in plasma, bone, or intestine of acutely nephrectomized rats. We conclude that, in the acutely nephrectomized living rat, 1,25-dihydroxyvitamin D3 is not present in plasma, bone, or intestine in quantities detectable by the sensitive techniques we have used. No conversion of 25-hydroxyvitamin D3 to 1,25-dihydroxyvitamin D3 was observed during a 24-hr period after nephrectomy of vitamin D-deprived rats. This fact casts doubt upon the significance of the in vitro production of 1,25-dihydroxyvitamin D3 by nonrenal cells as an in vivo phenomenon. Gray et al. (3), found that radiolabeled 1,25(OH)2D3 was absent from the tissues and plasma of acutely nephrectomized rats that had received low-specific-activity radiolabeled vitamin D3 or 25(OH)D3 immediately after nephrectomy. In human anephric subjects given radiolabeled vitamin D3, Mawer et aL (4) failed to detect radioactive 1,25(OH)2D3. Gray et al. (5) administered 25(OH)[3H]D3to 10 anephric subjects; in none of the patients studied was radiolabeled 1,25(OH)2D3 detected. In these human studies, radiolabeled 1,25(OH)2D3 was clearly detectable in normal subjects (4, 5). Lambert et al. (6) found recently that a substance was present in the plasma ofanephric subjects that displaced 1,25(OH)2[3H]D3 from its receptor; additionally, samples processed in a similar manner displaced 45Ca from labeled fetal bone in a bioassay system for 1,25(OH)2D3. The authors concluded that 1,25(OH)2D3 was present in the plasma of anephric subjects. However, other investigators, using radioreceptor, radioimmune, and biological assays for 1,25(OH)2D3, have been unable to detect 1,25(OH)2D3 in anephric persons (7-12).In certain situations, however, 1,25(OH)2D3 may be synthesized extrarenally. For example, a report by Barbour et al. (13) showed that an anephric subject with sarcoidosis had detectable plasma 1,25(OH)2D3-like material at a time when he was hypercalcemic (13)

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“…Specific, cytosolic binding proteins for 1 ,25-(OH)2-Da exist in the established target organs, e.g., intestine [ 1,2] and bone [3], as well as in other tissues [4-81, and these 'receptors' appear to transfer the hormone to the nucleus. A similar binding protein was detected in cytosol prepared from rat [9] and mouse skin [lo] suggesting the presence of a cutaneous 1 ,25-(OH)z-D,-receptor system.…”

Section: Introductionmentioning

confidence: 99%