title: Mineral Composition of Phosphate-Induced Calcification in a Rat Aortic Tissue Culture Model.
abstract: OBJECTIVE
  High phosphorus conditions promote vascular calcification (VC) in both chronic kidney disease (CKD) patients and experimental models. However, the composition of medial calcification has not been accurately determined, so the objective of this study was to evaluate the mineral composition of calcification in a tissue culture model, not a cell culture system.
  
  
  METHODS
  Aortic rings obtained from male Sprague-Dawley rats were incubated in serum-supplemented medium for 10 days. The inorganic phosphate (Pi) concentration of the medium was increased to induce VC, which was assessed by histology, imaging, and spectroscopy. The mineral composition of the calcification was analyzed using Fourier transform infrared (FTIR) spectroscopic imaging, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX) mapping.
  
  
  RESULTS
  The calcium content significantly increased only in aortic rings cultured for 10 days in the high-Pi medium (HiP: 3.8 mmol/L). The concentration of the phosphate transporter Pit-1 in the aortic tissue exposed to HiP was higher than that in the control incubated sections. The FTIR images and spectra indicated that PO4(3-) was mostly distributed as hydroxyapatite in the medial calcification of aortic rings cultured in HiP. A small quantity of carbonate was identified. The SEM-EDX overlay map demonstrated that phosphorus and calcium simultaneously accumulated and localized in the area of medial calcification induced by exposure to HiP.
  
  
  CONCLUSIONS
  This is the first report of accurate determination of the chemical composition of aortic medial calcification. Exposure to high Pi concentration augments aortic calcification via an increase in Pit-1, which mainly contains calcium phosphate.
authors.affiliation: Division of Nephrology, Department of Internal Medicine, Wakayama Medical University.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Sonou
authors.forename: Masaki
authors.initials: M
authors.lastname: Ohya
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Yashiro
authors.forename: Asuka
authors.initials: A
authors.lastname: Masumoto
authors.forename: Yuri
authors.initials: Y
authors.lastname: Nakashima
authors.forename: Teppei
authors.initials: T
authors.lastname: Ito
authors.forename: Toru
authors.initials: T
authors.lastname: Mima
authors.forename: Shigeo
authors.initials: S
authors.lastname: Negi
authors.forename: Hiromi
authors.initials: H
authors.lastname: Kimura-Suda
authors.forename: Takashi
authors.initials: T
authors.lastname: Shigematsu
mesh_terms: D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D002118:Calcium / Q000378:metabolism*; D008297:Male; D008855:Microscopy, Electron, Scanning; D008903:Minerals / Q000378:metabolism*; D008954:Models, Biological; D010710:Phosphates / Q000633:toxicity*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017550:Spectroscopy, Fourier Transform Infrared; D061205:Vascular Calcification / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology*
chemical_list: D008903:Minerals; D010710:Phosphates; D002118:Calcium