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The effect of L-ascorbic acid and/or tocopherol supplementation on electrophysiological parameters of the colon of rats chronically exposed to lead

Danuta I. Kosik-Bogacka, Irena Baranowska-Bosiacka, Mariola Marchlewicz, Agnieszka Kolasa, Katarzyna Jakubowska, Maria Olszewska, Natalia Lanocha, Ireneusz Wiernicki, Barbara Millo, Barbara Wiszniewska, Dariusz Chlubek

Med Sci Monit 2011; 17(1): BR16-26

DOI: 10.12659/MSM.881323

Available online: 2010-12-16

Published: 2010-12-16

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.
    Material/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.

Keywords: Spectrophotometry, Atomic, Organometallic Compounds - toxicity, Occludin, Membrane Proteins - metabolism, Rats, Ion Transport - drug effects, Electrophysiology, Dietary Supplements, Colon - physiology, Chromatography, High Pressure Liquid, Ascorbic Acid - pharmacology, Animals, Tocopherols - pharmacology, Water Pollutants, Chemical - toxicity