title: The effect of L-ascorbic acid and/or tocopherol supplementation on electrophysiological parameters of the colon of rats chronically exposed to lead.
abstract: BACKGROUND
  The aim of this study was to assess the effect of diet supplementation with L-ascorbic acid (500 mg/L), tocopherol (3 mg/kg b.w.), and/or a water soluble analog of tocopherol (Trolox) (48 mg/L) on ion transport in the colon of rats subjected to a chronic exposure (9 months) to 0.1% lead acetate in drinking water.
  
  
  METHODS
  The electrophysiological parameters of the colon wall were measured with Ussing methods. Lead content in the whole blood was analyzed by graphite furnace atomic absorption spectrometry (GFAAS) using Zeeman correction. L-ascorbic acid and tocopherol in plasma was measured by high performance liquid chromatography. Immunohistochemical reaction was carried out for visualization of occludin, the intracellular tight junction protein.
  
  
  RESULTS
  We showed a strong inhibitory effect of lead on the electrophysiological parameters, changes in intestinal permeability, disappearance of junctional occludin, decreased amount of mucus covering the colon surface, and the accumulation of PAS-positive substance in the apical region of the cytoplasm in the absorptive cells.
  
  
  CONCLUSIONS
  Supplementation with tocopherol or Trolox did not exert a beneficial influence on the studied parameters. L-ascorbic acid positively influenced the examined electrophysiological parameters, as it cancelled the inhibitory influence of lead on ion transport in the rat colon. L-ascorbic acid also protected against tight junction disruption of epithelial cells in the colon of the lead-treated rats. A similar effect was observed in the group of rats receiving lead and supplemented with L-ascorbic acid plus Trolox.
authors.affiliation: Department of Biology and Medical Parasitology, Pomeranian Medical University, Szczecin, Poland.
authors.forename: Danuta I
authors.initials: DI
authors.lastname: Kosik-Bogacka
authors.forename: Irena
authors.initials: I
authors.lastname: Baranowska-Bosiacka
authors.forename: Mariola
authors.initials: M
authors.lastname: Marchlewicz
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Kolasa
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Jakubowska
authors.forename: Maria
authors.initials: M
authors.lastname: Olszewska
authors.forename: Natalia
authors.initials: N
authors.lastname: Łanocha
authors.forename: Ireneusz
authors.initials: I
authors.lastname: Wiernicki
authors.forename: Barbara
authors.initials: B
authors.lastname: Millo
authors.forename: Barbara
authors.initials: B
authors.lastname: Wiszniewska
authors.forename: Dariusz
authors.initials: D
authors.lastname: Chlubek
mesh_terms: D000818:Animals; D001205:Ascorbic Acid / Q000097:blood / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D003106:Colon / Q000187:drug effects* / Q000502:physiology*; D019587:Dietary Supplements; D004594:Electrophysiology; D007150:Immunohistochemistry; D017136:Ion Transport / Q000187:drug effects; D008565:Membrane Proteins / Q000378:metabolism; D062793:Occludin; D009942:Organometallic Compounds / Q000097:blood / Q000633:toxicity*; D051381:Rats; D013054:Spectrophotometry, Atomic; D024505:Tocopherols / Q000097:blood / Q000494:pharmacology*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D008565:Membrane Proteins; D062793:Occludin; C568987:Ocln protein, rat; D009942:Organometallic Compounds; D014874:Water Pollutants, Chemical; D001205:Ascorbic Acid; D024505:Tocopherols; C008261:lead acetate