title: Constant or fluctuating hyperglycemias increases cytomembrane stiffness of human umbilical vein endothelial cells in culture: roles of cytoskeletal rearrangement and nitric oxide synthesis.
abstract: BACKGROUND
  Previous studies have implicated continuous or intermittent hyperglycemia in altered endothelium-derived nitric oxide (NO) synthesis. NO can regulate both the F-actin cytoskeleton and endothelial cell membrane stiffness. Atomic force microscopy (AFM) is a powerful tool that can be used to study plasma membrane deformability at the single cell level. As membrane stiffness is partially dependent on filamentous F-actin, the interdependence of these parameters can be studied through the combined approaches of AFM and laser scanning confocal microscopy (LSCM). In the present study, we evaluated the effects of constant or fluctuating hyperglycemia on endothelial-derived NO synthesis, the cytoskeletal contribution and endothelial cell membrane stiffness.
  
  
  RESULTS
  Compared to control cells cultured in low glucose (5 mM), constant (25 mM) or fluctuating (25/5 mM) high glucose significantly decreased NO release along with stiffening of endothelial cell membranes and F-actin rearrangement. The non-selective nitric oxide synthase (NOS) inhibitor, N(G)-nitro-(L)-arginine methyl ester ((L)-NAME) exerted similar effects on endothelial cells. Increasing concentrations of (L)-NAME (from 0.1 to 1 mM) exacerbated these effects in a concentration-dependent manner.
  
  
  CONCLUSIONS
  Result from the present study suggest that stiffening endothelial cell membranes are associated with decreased NO synthesis, which was established through the F-actin cytoskeletal redistribution. The precise mechanisms of hyperglycemia-induced endothelial dysfunction require further investigation.
authors.affiliation: The First Affiliated Hospital of Jinan University, Guangzhou, Guangdong, China.
authors.forename: Xianxian
authors.initials: X
authors.lastname: Chen
authors.forename: Lie
authors.initials: L
authors.lastname: Feng
authors.forename: Hua
authors.initials: H
authors.lastname: Jin
mesh_terms: D000199:Actins / Q000378:metabolism; D002462:Cell Membrane / Q000502:physiology*; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000503:physiopathology*; D005947:Glucose / Q000009:adverse effects / Q000494:pharmacology; D006801:Humans; D006943:Hyperglycemia / Q000139:chemically induced / Q000503:physiopathology*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D014471:Umbilical Veins / Q000166:cytology / Q000187:drug effects / Q000503:physiopathology
chemical_list: D000199:Actins; D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; D005947:Glucose; D019331:NG-Nitroarginine Methyl Ester