scholarly journals Effect of oestrogen and 1,25-dihydroxycholecalciferol on 25-hydroxycholecalciferol metabolism in primary chick kidney-cell cultures

1978 ◽  
Vol 174 (1) ◽  
pp. 231-236 ◽  
Author(s):  
E Spanos ◽  
D I Barrett ◽  
K T Chong ◽  
I MacIntyre
Keyword(s):  
Vitamin D ◽  
Cell Cultures ◽  
Kidney Cell ◽  
Primary Cultures ◽  
Kidney Cells ◽  
Hydroxylase Activity ◽  
Experimental Conditions ◽  
Polar Metabolites ◽  
Chick Kidney ◽  
25 Hydroxycholecalciferol

Primary cultures of chick kidney cells convert 25-hydroxycholecalciferol into more-polar metabolites. Cells from vitamin D-deficient chicks have high 25-hydroxycholecalciferol 1 alpha-hydroxylase (1 alpha-hydroxylase) activity, but no 25-hydroxycholecalciferol 24-hydroxylase (24-hydroxylase) activity. Physiological concentrations of 1,25-dihydroxycholeclaciferol suppress 1 alpha-hydroxylase and induce 24-hydroxylase activity. The inhibition of 1 alpha-hydroxylase preceded the induction of 24-hydroxylase. In contrast, oestradiol-17 beta had no effect on the activity of either hydroxylase under a variety of experimental conditions. These results clearly demonstrate that 1,25-dihydroxycholecalciferol, but not oestrogen, acts directly on the kidney cells to regulate the metabolism of 25-hydroxycholecalciferol.

25(OH)D3 metabolism in kidney cell cultures: lack of a direct effect of estradiol

1981 ◽  
Vol 240 (2) ◽  
pp. E119-E124 ◽  
Author(s):  
H. L. Henry
Keyword(s):  
Direct Effect ◽  
Cell Cultures ◽  
Kidney Cell ◽  
Renal Cell ◽  
Primary Cultures ◽  
Kidney Cells ◽  
Hydroxylase Activity ◽  
Dihydroxyvitamin D3 ◽  
Chick Kidney

There are several reports of increased production of 1 alpha,25-dihydroxyvitamin D3 [1,25(OH)2D3] by the kidney of birds in response to estrogen treatment. To determine whether estradiol influences the renal cell directly, primary cultures of chick kidney cells were exposed to the steroid under a variety of conditions. In the absence of 1,25(OH)2D3, treatment of cultures for 20-24 h with 10(-5) and 10(-6) M estradiol led to inhibition of 25-hydroxyvitamin D3 [25(OH)D3]-1-hydroxylase activity. When the 1-hydroxylase was suppressed and 25(OH)2D3-24-hydroxylase was induced by treatment with 1,25(OH)2D3, estradiol in concentrations of 10(-9) and 10(-5) M either had no effect or slightly inhibited 1,25(OH)2D3 production. Similarly, 24R,25-dihydroxyvitamin D3[24,25(OH)2D3] production was not affected consistently by estradiol. These results were unaltered when either testosterone (10(-6) M) or insulin (5 micrograms/ml) was present in the medium. Shorter treatments (0.5, 2, 4, and 8 h) with estradiol resulted in a transient decrease in both 1,25(OH)2D3 and 24,25(OH)2D3 production, but at no time was stimulation observed. These results suggest that the effects of estrogens on 25(OH)D3 metabolism observed in vivo are exerted elsewhere than directly at the renal cell.

Feedback Regulation of 25-Hydroxycholecalciferol Metabolism by Vitamin D3

1975 ◽  
Vol 48 (3) ◽  
pp. 227-230
Author(s):  
I. M. A. Evans ◽  
K. W. Colston ◽  
L. Galante ◽  
I. MacIntyre
Keyword(s):  
Vitamin D ◽  
Vitamin D3 ◽  
Actinomycin D ◽  
Feedback Regulation ◽  
Kidney Cells ◽  
Hydroxylase Activity ◽  
25 Hydroxycholecalciferol

1. In vitamin D-deficient chicks both vitamin D3 and 1α-hydroxycholecalciferol markedly decrease renal 1-hydroxylase activity and induce 24-hydroxylase activity. 2. Actinomycin D abolishes both effects. 3. These results are consistent with feedback regulation of vitamin D3 metabolism by a direct nuclear action of the vitamin or its metabolites on the kidney cells.

Effect of Phenobarbitone Treatment on Vitamin D Metabolism in Mammals

1974 ◽  
Vol 46 (4) ◽  
pp. 433-448 ◽  
Author(s):  
J. Silver ◽  
G. Neale ◽  
G. R. Thompson
Keyword(s):  
Vitamin D ◽  
Biological Activity ◽  
Silicic Acid ◽  
Vitamin D3 ◽  
Water Soluble ◽  
Prolonged Treatment ◽  
Vitamin D Metabolism ◽  
Silicic Acid Chromatography ◽  
Polar Metabolites ◽  
25 Hydroxycholecalciferol

1. The metabolism of radioactive cholecalciferol was studied in control and phenobarbitone-treated rats and pigs. 2. Treatment with phenobarbitone enhanced the appearance in plasma of 25-hydroxycholecalciferol (peak IV on silicic acid chromatography), and of more-polar metabolites (peak V), but not of the most-polar metabolites (peak VI). Peak IV had the chromatographic properties of authentic 25-hydroxycholecalciferol (25-HCC) and had biological activity. 3. There was no effect on the appearance of peaks V and VI in plasma after an injection of radioactive 25-HCC. 4. Treatment with phenobarbitone enhanced the excretion of metabolites of radioactive vitamin D3 in bile. These metabolites were largely water-soluble conjugates of peaks IV, V and VI, which included glucuronides. Peak IV in bile was not identical with 25-HCC. 5. Prolonged treatment with phenobarbitone depleted the tissue radioactivity of rats given radioactive vitamin D3.

Repression of a G0-associated 65-kilodalton protein in actively proliferating and SV40-transformed mouse kidney cells

1992 ◽  
Vol 70 (2) ◽  
pp. 149-155 ◽  
Author(s):  
Timothy M. Rose ◽  
Sandra Tremblay ◽  
Edward W. Khandjian
Keyword(s):  
Primary Cultures ◽  
Growth Arrest ◽  
Mouse Kidney ◽  
Specific Gene ◽  
Nuclear Fraction ◽  
Quiescent State ◽  
Kidney Cells ◽  
Experimental Conditions ◽  
Two Dimensional Gel Electrophoresis ◽  
Mouse Cells

The pattern of [35S]methionine-labeled proteins from primary cultures of mouse kidney epithelial cells arrested in G0 phase was analyzed by two-dimensional gel electrophoresis and compared with that observed from cultures of actively proliferating and SV40-transformed mouse kidney cells. A major polypeptide (p65) migrating with a molecular mass of 65 000 daltons and a pI of 5.8 was detected in quiescent cultures of cells which had exhausted their finite division potential. Under the experimental conditions used, these cells had lost sensitivity to growth factors and were irreversibly blocked in G0 phase of the cell cycle. In cultures of actively proliferating mouse kidney cells, the expression of p65 was not observed until just prior to arrest. Moreover, proliferating cultures of immortalized mouse kidney cells that had been reactivated from their quiescent state by infection with SV40 did not express p65. Subcellular localization studies suggest that p65 is associated with the crude nuclear fraction. In addition, p65 is glycosylated and binds the lectin concanavalin A. Pulse–chase experiments demonstrated that p65 was short lived with an estimated half life of 10 min. Thus, p65 appears to be a growth-arrest specific gene product whose expression is repressed during the proliferative state of mitotically active mouse kidney cells.Key words: G0 phase, senescence, proliferation, quiescence, SV40-transformed mouse cells.

scholarly journals Investigations on metabolites of vitamin D in rat bile. Separation and partial identification of a major metabolite

1969 ◽  
Vol 115 (4) ◽  
pp. 663-669 ◽  
Author(s):  
P. A. Bell ◽  
E. Kodicek
Keyword(s):  
Vitamin D ◽  
Silicic Acid ◽  
Intravenous Infusion ◽  
Similar Pattern ◽  
Bile Ducts ◽  
Gradient Elution ◽  
Partial Identification ◽  
Polar Metabolites ◽  
Rat Bile ◽  
25 Hydroxycholecalciferol

1. Young rats with cannulated bile ducts were given 0·34mg. of [1α−3H]cholecalciferol or 0·54mg. of [14C]ergocalciferol by intravenous infusion. Of the radioactivity in the dose of [1α−3H]cholecalciferol 31% was recovered in bile within 24hr. 2. The metabolites in bile were separated by gradient-elution column chromatography on silicic acid into five components, all more polar than cholecalciferol or 25-hydroxycholecalciferol. [14C]Ergocalciferol gave a similar pattern of metabolites in bile. 3. The three most polar metabolites were shown to be ionic. The major component has been identified as a glucuronide conjugate, which was not identical with synthetic cholecalciferyl glucuronide.

Submitochondrial localization of kidney 25-hydroxycholecalciferol 1α-hydroxylase in vitamin D repleted weanling guinea pigs

1987 ◽  
Vol 65 (7) ◽  
pp. 673-676 ◽  
Author(s):  
Xue Yan ◽  
Guy Charette ◽  
Edgard E. Delvin
Keyword(s):  
Vitamin D ◽  
Cytochrome C ◽  
Guinea Pig ◽  
Guinea Pigs ◽  
Membrane Fraction ◽  
Hydroxylase Activity ◽  
Oxidoreductase Activity ◽  
Pig Kidney ◽  
Steroid Hydroxylases ◽  
25 Hydroxycholecalciferol

We have studied the submitochondrial localization of guinea-pig kidney 25-hydroxycholecalciferol 1α-hydroxylase. Treatment of the mitochondrial-enriched fraction with recrystallized digitonin produced mitoplasts bordered by a single membrane and with intact matrix. They contained nearly 90% of the 25-hydroxycholecalciferol 1α-hydroxylase activity and nearly 100% of the cytochrome-c: oxygen oxidoreductase. Amine: oxygen oxidoreductase activity remained mainly in the outer membrane fraction. These data show that 25-hydroxycholecalciferol 1α-hydroxylase has a distribution similar to that of steroid hydroxylases.

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