Hydrogen peroxide enhanced Ca²⁺-activated BK currents and promoted cell injury in human dermal fibroblasts

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• 作者：Bing Feng^a ; ^b ; Wen-Lei Ye^c ; Lai-ji Ma^b ; Yun Fang^a ; Yan-Ai Mei^c ; Shao-Min Wei^a ; ^b ; ^{weishaomin@jahwa.com.cn}
• 关键词：Hydrogen peroxide ; Ca2+-activated BK channels ; Human dermal fibroblasts ; Cell injury
• 刊名：Life Sciences
• 出版年：2012
• 期刊代码：62_00243205
• 类别：imm
• 出版时间：10 March, 2012
• 卷：90
• 期：11-12
• 页码：424-431
• 文件大小：1220 K

摘要

Aims

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 (H₂O₂), an oxidative stress inducer, could modulate these channels or induce human dermal fibroblasts injury.

Main methods

The effects of H₂O₂ 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.

Key findings

Treatment of cells with 100 渭M H₂O₂ 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 H₂O₂-induced increase in K⁺ currents was mimicked by a PKC activator, and was blocked by the PKC inhibitor or the large conductance Ca²⁺-activited K⁺ (BK) channel blockers. The intracellular PKC levels were significantly enhanced by H₂O₂ treatment in a concentration-dependent manner. After exposure to H₂O₂, 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 H₂O₂-induced human dermal fibroblasts injury.

Significance

Our results revealed that H₂O₂ could enhance BK currents by PKC pathway. Increased K⁺ currents might be related to H₂O₂-induced human dermal fibroblasts injury. The results reported here contribute to our understanding of the mechanism underlying H₂O₂-induced human dermal fibroblasts injury.