title: [Damage mechanism of intermittent exposure to high concentrations of glucose to beta cell lines (HIT-T15 cell)].
abstract: OBJECTIVE
  To test the effect of intermittent exposure to high concentrations of glucose on HIT-T15 cells.
  
  
  METHODS
  The HIT-T15 cells (pancreatic beta cell lines) were exposed to 16.7 mmol/L of glucose for two hours, at an interval of three hours. Such intermittent exposure was repeated three times a day. Otherwise, the cells were exposed to 5.5 mmol/L of glucose. The control groups included continuing exposure to 5.5 mmol/L of glucose (normal control group) and continuing exposure to 16.7 mmol/L of glucose. The impact of N-acetyl-L-cysteine (NAC) was also tested in the groups with intermittent and continuing exposure to 16. 7 mmol/L of glucose. The insulin was detected by radioimmunoassay (RIA). The mitochondrial membrane potential (MMP) was measured by laser scanning confocal microscope. The ATP levels of beta cells were examined by the luciferin-luciferase kit. The Malonaldehyde (MDA) was measured through thiobarbituric acid reaction (TBA). The intracellular reactive oxygen species (ROS) was observed by flow cytometry.
  
  
  RESULTS
  The HIT-T15 cells exposed to intermittent and continuing high glucose secreted [(3.13 +/- 1.11) microIU/mLD and [(5.18 +/- 0. 95) microIU/mL] of insulin, significantly less than the control [(9.33 +/- 0.62) microIU/mL, P < 0.05]. The MDA and ROS levels increased while the ATP and MMP levels decreased significantly in the cells exposed to intermittent and continuing high glucose (P < 0.05). The cells exposed to intermittent high glucose produced more ROS than the cells exposed to continuing high glucose (P < 0.05).
  
  
  CONCLUSIONS
  Exposure of HIT-T15 to high glucose leads to oxidative stress of mitochondrial. Intermittent exposure causes more serious stress than continuing exposure. Such response might be a result of decreased MMP level and ATP contents.
authors.affiliation: Department of Endocrinology, West China Hospital, Sichuan University, Chengdu 610041, Chnia.
authors.forename: Ping
authors.initials: P
authors.lastname: Qiu
authors.forename: Tie-yun
authors.initials: TY
authors.lastname: Zhao
authors.forename: Xiu-jun
authors.initials: XJ
authors.lastname: Li
authors.forename: Su-yi
authors.initials: SY
authors.lastname: Liu
authors.forename: Xiao-yu
authors.initials: XY
authors.lastname: Li
mesh_terms: D002460:Cell Line; D005947:Glucose / Q000494:pharmacology*; D006801:Humans; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000187:drug effects*; D008315:Malondialdehyde / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D018384:Oxidative Stress; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D007328:Insulin; D017382:Reactive Oxygen Species; D008315:Malondialdehyde; D005947:Glucose