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Biphasic effects of H(2)O(2) on BK(Ca) channels
Bo Liu1, Xiaohui Sun, Yanhong Zhu
1Huazhong University of Science and Technology, Wuhan, PR China.
Free Radical Research
|June 22, 2010
Summary
Hydrogen peroxide (H2O2) has dual effects on large conductance calcium-dependent potassium (BKCa) channels. H2O2 inhibits BKCa channels in isolated patches but activates them in cell-attached patches, involving PI3K/AKT signaling in vasodilation.
Area of Science:
- Biophysics
- Molecular Biology
- Cell Physiology
Background:
- Hydrogen peroxide (H2O2) exhibits varied effects on large conductance calcium and voltage-dependent potassium (BKCa) channels.
- The precise mechanisms underlying H2O2's influence on BKCa channel activity remain incompletely understood.
Purpose of the Study:
- To elucidate the differential effects of H2O2 on BKCa channel activity.
- To investigate the signaling pathways involved in H2O2-mediated BKCa channel modulation and vasodilation.
Main Methods:
- Heterologous expression of mouse Slo-encoded BKCa channels in HEK 293 cells.
- Electrophysiological recordings (inside-out and cell-attached patches) to measure BKCa channel activity.
- Investigation of the role of PI3K/AKT signaling pathway.
Main Results:
- H2O2 inhibited BKCa channel activity in inside-out patches, suggesting potential oxidative modification of channel proteins or associated regulators.
- H2O2 enhanced BKCa channel activity in cell-attached patches, indicating a signaling-dependent mechanism.
- PI3K/AKT signaling pathway was identified as a key modulator of H2O2-induced BKCa channel activation.
- Both BKCa channels and the PI3K pathway are implicated in H2O2-induced vasodilation, with PI3K-mediated vasodilation primarily occurring through BKCa channel modulation.
Conclusions:
- H2O2 exerts opposing effects on BKCa channel activity depending on the experimental configuration (direct vs. signaling-dependent).
- Oxidative modification of cysteine residues may contribute to H2O2-induced inhibition.
- PI3K/AKT signaling mediates H2O2-induced BKCa channel activation and subsequent vasodilation.
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