Bednarczyk 2014 Abstract IOC96

Bednarczyk P (2014) Coupling of the mitochondrial BKCa channel to the respiratory chain.

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Bednarczyk P, Siemen D, Szewczyk A (2014)

Event: IOC96

Potassium channels as present in the plasma membrane of various cells have also been found in the inner mitochondrial membrane. Potassium channels have been proposed to regulate the mitochondrial membrane potential, respiration, matrix volume and Ca2+ ion homeostasis. It has been suggested that mitochondrial potassium channels participate in ischemic preconditioning and neurodegenerative disorders. In our study single channel activity of a large conductance Ca2+-regulated potassium channel was measured by patch-clamp of mitoplasts isolated from an astrocytoma cell line. A potassium selective current was recorded with a mean conductance of 290 pS in symmetrical 150 mM KCl solution. The channel was activated by Ca2+ at micromolar concentrations and inhibited irreversibly by iberiotoxin, an selective inhibitor of the BKCa channel. Additionally, we showed that substrates of the respiratory chain like NADH, succinate, and glutamate/malate, decrease the activity of the channel at positive voltages. The effect was abolished by rotenone, antimycin and cyanide, being inhibitors of respiratory chain. Our findings indicate that mitochondrial large conductance Ca2+-regulated potassium channels with properties similar to the surface membrane BKCa channel are present in human astrocytoma mitochondria and can be stimulated by redox status of the respiratory chain.

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