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Updated: Jul 15, 2026
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A Flow Cytometry-based Assay for Measuring Mitochondrial Membrane Potential in Cardiac Myocytes After Hypoxia/Reoxygenation
Published on: July 13, 2018
Hypoxia increases BK channel activity in the inner mitochondrial membrane
Xiang Q Gu1, Detlef Siemen, Suhel Parvez
1Department of Pediatrics (Section of Respiratory Medicine), University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0735, USA.
Summary
The BK channel in mitochondria opens more during hypoxia, increasing potassium (K+) efflux. This mitochondrial K+ efflux may help maintain cytosolic K+ levels during low oxygen conditions.
Area of Science:
- Mitochondrial physiology
- Ion channel function
- Cellular response to hypoxia
Background:
- The BK channel, a large-conductance potassium channel, is crucial in various cellular functions.
- Its role in the inner mitochondrial membrane, particularly under stress conditions like hypoxia, remains incompletely understood.
Purpose of the Study:
- To investigate the function of the BK channel in the inner mitochondrial membrane.
- To determine how BK channel activity changes under physiological and hypoxic conditions.
Main Methods:
- Utilized on-mitoplast and whole-mitoplast patch-clamp techniques.
- Characterized single BK channel conductance, Ca(2+)- and voltage-dependence, and charybdotoxin inhibition.
Main Results:
- BK channels in the inner mitochondrial membrane exhibit properties similar to plasma membrane BK channels.
- Hypoxia significantly increased the open probability of mitochondrial BK channels.
- Hypoxia caused a positive shift in the reversal potential without altering channel conductance.
Conclusions:
- Mitochondrial BK channels are active and regulated by hypoxia.
- Hypoxia-induced increase in BK channel open probability leads to K+ efflux from the mitochondrial matrix.
- This efflux may play a role in maintaining cytosolic K+ homeostasis during hypoxia.
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