Local action of phosphate depletion and insulin-like growth factor 1 on in vitro production of 1,25-dihydroxyvitamin D by cultured mammalian kidney cells
| Autor: | L Condamine, Gérard Friedlander, F. Vrtovsnik, Michèle Garabédian, C. Menaa |
|---|---|
| Rok vydání: | 1994 |
| Předmět: |
medicine.medical_specialty
Swine medicine.medical_treatment Cell Biology Kidney Phosphates Kidney Tubules Proximal chemistry.chemical_compound Insulin-like growth factor In vivo Internal medicine medicine Animals Insulin-Like Growth Factor I Cells Cultured Growth factor Kidney metabolism Opossums General Medicine Phosphate In vitro Culture Media Endocrinology medicine.anatomical_structure chemistry Dihydroxycholecalciferols LLC-PK1 Cells Rabbits Research Article |
| Zdroj: | Journal of Clinical Investigation. 94:1673-1679 |
| ISSN: | 0021-9738 |
| DOI: | 10.1172/jci117512 |
| Popis: | The hormonal form of vitamin D, 1,25(OH)2D, is synthesized mostly in proximal renal tubular cells. Experimental and clinical studies suggest that the growth hormone may be involved in growth-related fluctuations of plasma 1,25(OH)2D and in the increase of 1,25(OH)2D induced by in vivo phosphate deprivation, an action possibly mediated by insulin-like growth factor 1 (IGF 1). We tested the effects of phosphate depletion and IGF 1 addition on 1,25(OH)2D3 production in cultured kidney cells: opossum kidney (OK) cells, LLC-PK 1, and rabbit's proximal tubular cells. Confluent cell monolayers were preincubated in various phosphate concentrations, in the presence and absence of IGF 1. Then, 5 nM of [3H]25 (OH)D3 or 2 microM of 25 (OH)D3 were added to the medium and the cells were incubated for a further 120 min. The amount of biosynthesized 1,25(OH)2D3 in lipid extracts was determined after two different straight phase high performance liquid chromatographies. The experiment showed the following: (a) LLC-PK 1 and rabbit's cells expressed a detectable ability to synthesize 1,25(OH)2D3, while OK cells did not. (b) Partial or total phosphate deprivation increased the amount of 1,25(OH)2D3 produced, respectively in LLC-PK 1 and in rabbit's cells. (c) IGF 1 (25 ng/ml) increased 1,25(OH)2D3 production in rabbit's cells, particularly in phosphate-free medium (1.6-fold), and in LLC-PK 1 cells, in partial phosphate depletion (2.75-fold in 1 mM phosphate, P = 0.015, n = 5, and 3.2-fold in 0.5 mM phosphate, P = 0.043, n = 4). Our findings demonstrate a local action of phosphate depletion and of IGF 1 on 1,25-dihydroxyvitamin D3 production. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|