title: Hydrogen peroxide enhanced Ca(2+)-activated BK currents and promoted cell injury in human dermal fibroblasts.
abstract: OBJECTIVE
  Recent studies have shown that dermal fibroblasts possess multiple types of voltage-dependent K(+) channels, and the activation of these channels induces apoptosis. In the present study, we aimed to investigate whether hydrogen peroxide (H(2)O(2)), an oxidative stress inducer, could modulate these channels or induce human dermal fibroblasts injury.
  
  
  METHODS
  The effects of H(2)O(2) on K(+) currents were studied using a whole-cell recording. Intracellular PKC levels were measured with a direct human PKC enzyme immunoassay kit. Cell viability was assessed using PI staining and apoptotic nuclei were detected with TdT-mediated digoxigenin-dUTP nick-end labelling assay (TUNEL) assay.
  
  
  RESULTS
  Treatment of cells with 100μM H(2)O(2) resulted in a partially reversible increase in non-inactivating outward K(+) currents and an alteration in the steady-state activation property of the channels. The H(2)O(2)-induced increase in K(+) currents was mimicked by a PKC activator, and was blocked by the PKC inhibitor or the large conductance Ca(2+)-activited K(+) (BK) channel blockers. The intracellular PKC levels were significantly enhanced by H(2)O(2) treatment in a concentration-dependent manner. After exposure to H(2)O(2), evaluation of fibroblasts survival rate and damaged cell number with TUNEL-positive nuclei revealed an increased cell injury. Blocking the K(+) channels with blockers significantly decreased the H(2)O(2)-induced human dermal fibroblasts injury.
  
  
  CONCLUSIONS
  Our results revealed that H(2)O(2) could enhance BK currents by PKC pathway. Increased K(+) currents might be related to H(2)O(2)-induced human dermal fibroblasts injury. The results reported here contribute to our understanding of the mechanism underlying H(2)O(2)-induced human dermal fibroblasts injury.
authors.affiliation: School of Chemical and Material Engineering, Jiangnan University, Wuxi, Jiangsu 214122, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Feng
authors.forename: Wen-Lei
authors.initials: WL
authors.lastname: Ye
authors.forename: Lai-ji
authors.initials: LJ
authors.lastname: Ma
authors.forename: Yun
authors.initials: Y
authors.lastname: Fang
authors.forename: Yan-Ai
authors.initials: YA
authors.lastname: Mei
authors.forename: Shao-Min
authors.initials: SM
authors.lastname: Wei
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D020405:Dermis / Q000166:cytology / Q000378:metabolism*; D005347:Fibroblasts / Q000378:metabolism*; D006801:Humans; D006861:Hydrogen Peroxide / Q000633:toxicity*; D007124:Immunoenzyme Techniques; D020287:In Situ Nick-End Labeling; D018408:Patch-Clamp Techniques; D024681:Potassium Channels, Calcium-Activated / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism
chemical_list: D024681:Potassium Channels, Calcium-Activated; D006861:Hydrogen Peroxide; D011493:Protein Kinase C