title: Effect of beta-carotene on oxidative stress and expression of cardiac connexin 43.
abstract: BACKGROUND
  Intervention studies have shown an increased mortality in patients who received beta-carotene. However, the mechanisms involved in this phenomenon are still unknown.
  
  
  OBJECTIVE
  Evaluate the influence of beta-carotene on oxidative stress and the expression of connexin 43 in rat hearts.
  
  
  METHODS
  Wistar rats, weighing approximately 100 g, were allocated in two groups: CONTROL GROUP (n=30), that received the diet routinely used in our laboratory, and Beta-Carotene Group (n = 28), which received beta-carotene (in crystal form, added and mixed to the diet) at a dose of 500 mg of beta-carotene/kg of diet. The animals received the treatment until they reached 200-250 g, when they were sacrificed. Samples of blood, liver and heart were collected to perform Western blotting and immunohistochemistry for connexin 43; morphometric studies, dosages of beta-carotene by high-performance liquid chromatography as well as reduced glutathione, oxidized glutathione and lipids hydroperoxides were performed by biochemical analysis.
  
  
  RESULTS
  Beta-carotene was detected only in the liver of Beta-Carotene Group animals (288 ± 94.7 µg/kg). Levels of reduced/oxidized glutathione were higher in the liver and heart of Beta-Carotene Group animals (liver -
  
  
  METHODS
  42.60 ± 1.62; liver - Beta-Carotene Group: 57.40 ± 5.90; p = 0.04; heart: -
  
  
  METHODS
  117.40 ± 1.01; heart - Beta-Carotene Group: 121.81 ± 1.32 nmol/mg protein; p = 0.03). The content of total connexin 43 was larger in Beta-Carotene Group.
  
  
  CONCLUSIONS
  Beta-carotene demonstrated a positive effect, characterized by the increase of intercellular communication and improvement of anti-oxidizing defense system. In this model, mechanism does not explain the increased mortality rate observed with the beta-carotene supplementation in clinical studies.
authors.forename: Rosangela
authors.initials: R
authors.lastname: Novo
authors.forename: Paula S
authors.initials: PS
authors.lastname: Azevedo
authors.forename: Marcos F
authors.initials: MF
authors.lastname: Minicucci
authors.forename: Leonardo A M
authors.initials: LA
authors.lastname: Zornoff
authors.forename: Sergio A R
authors.initials: SA
authors.lastname: Paiva
mesh_terms: D000818:Animals; D015153:Blotting, Western; D018031:Connexin 43 / Q000187:drug effects* / Q000378:metabolism; D019803:Glutathione Disulfide / Q000032:analysis; D006352:Heart Ventricles / Q000737:chemistry; D007150:Immunohistochemistry; D008054:Lipid Peroxides / Q000032:analysis; D008099:Liver / Q000737:chemistry; D008297:Male; D018384:Oxidative Stress / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar; D020257:Ventricular Remodeling; D014815:Vitamins / Q000009:adverse effects / Q000032:analysis / Q000494:pharmacology*; D019207:beta Carotene / Q000009:adverse effects / Q000032:analysis / Q000494:pharmacology*
chemical_list: D018031:Connexin 43; D008054:Lipid Peroxides; D014815:Vitamins; D019207:beta Carotene; D019803:Glutathione Disulfide
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