Extraction of Vitamin D Metabolites by Bones of Normal Adult Dogs

Ølgaard, Klaus; Schwartz, John H.; Finco, Delmar R.; Arbelaez, Mario; Haddad, John G.; Lv, Avioli; Klahr, Saulo; Slatopolsky, Eduardo

doi:10.1172/jci110496

Cited by 11 publications

(3 citation statements)

References 24 publications

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“…The bovine albumin was fraction V-Pentex (Miles Laboratory, Elkhart, IN). This albumin has been shown in other studies (Olgaard et al, 1982) not to contain contaminations of vitamin D-binding protein. The vitamin D derivatives were suspended in 50 pI of absolute ethanol followed by suspension in 150 IJ.~ of 5% bovine albumin; 20 p1 of this mixture was then added to 225 IJ.~ of either serum or 5 g/dl bovine albumin for the carotid artery injection solution.…”

Section: Addition Of Isotope To Human Serumsupporting

confidence: 65%

“…This low concentration of albumin was added to the Ringer's solution because of the instability of the vitamin D derivatives in protein-free aqueous solution (Haddad and Chyu, 1971). The low extraction,~ e.g., I%, of 1,25-(OH),D, caused by serum ( Table 1 ) is also seen in dog brain capillaries (Gascon-Barre and Huet, 1983), and in the perfused dog tibia preparation (Olgaard et al, 1982). The results obtained with I3H]retinoic acid ( Table 1) are very similar to previously published studies on the BBB transport of palmitic acid, as the extraction of retinoic acid and palmitic acid in Ringer's (0.1 g/dl albumin) is 19 t I % (Table I ) and 12 +-1% (Pardridge and Mietus, 1980), respectively.…”

Section: Discussionmentioning

confidence: 99%

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Restricted Transport of Vitamin D and A Derivatives Through the Rat Blood‐Brain Barrier

Pardridge

Sakiyama

Coty

1985

Journal of Neurochemistry

117

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The present studies measure the transport of retinol, retinoic acid, 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3], and 25-hydroxyvitamin D3 [25-(OH)D3] through the rat brain capillary endothelial wall, i.e., the blood-brain barrier (BBB). The vitamin A and D derivatives bind both to albumin and to specific high-affinity binding proteins in plasma. In the presence of physiologic concentrations of plasma proteins, the extraction by brain of all four compounds was 5% or less.

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Section: Addition Of Isotope To Human Serumsupporting

confidence: 65%

Section: Discussionmentioning

confidence: 99%

Restricted Transport of Vitamin D and A Derivatives Through the Rat Blood‐Brain Barrier

Pardridge

Sakiyama

Coty

1985

Journal of Neurochemistry

117

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“…Decreased DBP and increased unbound 25OHD 3 concentrations favor the uptake of 25OHD 3 by the kidney (36). Increased substrate availability and/or a decreased DBP concentration would temporarily increase the bioavailability of (unbound) 1,25-(OH) 2 D 3 (37)(38)(39) and suppress the renal la-hydroxylase (40,41) until the free 1,25-(OH) 2 D 3 level is again within normal limits. This is compatible with the high to normal diffusible serum calcium concentrations and agrees with previous studies which documented normal or increased serum calcium and intestinal calcium absorption in diabetic rats (7) and man (17,18).…”

Section: Discussionmentioning

confidence: 99%

1,25-Dihydroxyvitamin D and Vitamin D-Binding Protein Are Both Decreased in Streptozotocin-Diabetic Rats*

et al. 1985

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Calcium and vitamin D metabolism were studied in streptozotocin-treated rats up to 10 days after the induction of diabetes. Proteinuria, hypercalciuria, and hyperphosphaturia appeared as early as 3 days after diabetes induction and were reversed by insulin. The serum proteins and fasting calcium concentrations were decreased in untreated diabetic rats. The concentration of serum vitamin D binding protein (DBP) was higher in male than in female control rats (mean +/- SD; 555 +/- 73 vs. 348 +/- 28 mg/liter, P less than 0.001). When sequentially measured in male untreated diabetic rats, DBP concentration steadily decreased. Compared with control values, DBP was reduced 19%, 28%, and 32% on days 3, 6, and 10, respectively, after induction of diabetes in male rats. In female animals, DBP was reduced 22% on day 10 of diabetes. DBP concentration was corrected by insulin treatment of diabetic rats and remained normal in streptozotocin-treated animals that did not develop diabetes. The serum concentration of 25-hydroxyvitamin D3 was similar in both sexes and was not affected by diabetes. Like DBP, the concentration of total 1,25-dihydroxyvitamin D3 [1,25-(OH)2D3] was higher in male than in female control rats (120 +/- 24 vs. 96 +/- 17 ng/liter, P less than 0.001), but 10 days after induction of diabetes this concentration decreased by 37% and 29% in male and female rats, respectively. The free 1,25-(OH)2D3 concentration, estimated from the molar 1,25-(OH)2D3/DBP ratio, was similar in both sexes and was not decreased by diabetes. We conclude that experimental diabetes in the rat induces a decrease in DBP concentration and a concomitant decrease in total but not in free 1,25-(OH)2D3 concentrations. This may indicate that diabetes decreases circulating 1,25-(OH)2D3 concentrations through alterations in DBP levels.

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Vitamin D Endocrine System and Calcium and Phosphorus Homeostasis

Gross

Kumar

1992

Comprehensive Physiology

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The sections in this article are: Physiological Effects of Vitamin D and its Active Metabolites on Calcium and Phosphorus Homeostasis Sources of Vitamin D Transport of Vitamin D and its Metabolites in Plasma Metabolism of Vitamin D 3 to 25‐Hydroxyvitamin D 3 Metabolism of 25‐Hydroxyvitamin D 3 Regulation of the 25‐Hydroxyvitamin D 3 –1α‐Hydroxylase Enzyme Parathyroid Hormone Phosphorus Concentrations Calcium: Direct Effects 1,25‐Dihydroxyvitamin D 3 Calcitonin Hydrogen Ion Sex Steroids Glucocorticoids Pituitary Hormones Thyroid Hormone Pregnancy Catabolism of 1,25‐Dihydroxyvitamin D 3 Physiological Adaptations that Occur in Response to Changes in Serum Calcium and Phosphate Concentrations Hypocalcemia and Hypercalcemia Hypophosphatemia and Hyperphosphatemia Pathophysiology and Physiology of the 1,25‐Dihydroxyvitamin D 3 System Mechanisms of Action of 1,25‐Dihydroxyvitamin D 3 1,25‐Dihydroxyvitamin D 3 in the Intestine Processes in the Cell That Are Mediated by 1,25‐Dihydroxyvitamin D 3 Intestinal Brush Border Events Induced by 1,25‐Dihydroxyvitamin D 3 Events at the Contraluminal Border Effects of 1,25‐Dihydroxyvitamin D 3 on the Intestinal Cell 1,25‐Dihydroxyvitamin D 3 in the Kidney

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Extraction of Vitamin D Metabolites by Bones of Normal Adult Dogs

Cited by 11 publications

References 24 publications

Restricted Transport of Vitamin D and A Derivatives Through the Rat Blood‐Brain Barrier

Restricted Transport of Vitamin D and A Derivatives Through the Rat Blood‐Brain Barrier

1,25-Dihydroxyvitamin D and Vitamin D-Binding Protein Are Both Decreased in Streptozotocin-Diabetic Rats*

Vitamin D Endocrine System and Calcium and Phosphorus Homeostasis

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