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

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 mu 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. (C) 2012 Elsevier Inc. All rights reserved.