A new brain mitochondrial sodium-sensitive potassium channel: effect of sodium ions on respiratory chain activity

Abstract

We have determined the electropharmacological properties of a new potassium channel from brain mitochondrial membrane by planar lipid bilayer method. Our results showed the presence of a channel with a conductance of 150 pS at potentials between 0 and −60 mV in 200 cis/50 trans mM KCl solutions. The channel was voltage-independent, with an open probability value ∼0.6 at different voltages. ATP did not affect current amplitude and Po at positive and negative voltages. Notably, adding iberiotoxin, charybdotoxin, lidocaine, and margatoxin had no effect on the channel behavior. Similarly, no changes were observed by decreasing the cis-pH to 6. Interestingly, the channel was inhibited by adding sodium in a dose dependent manner. Our results also indicated a significant increase in mitochondrial complex IV activity and membrane potential and decrease in complex I activity and mitochondrial ROS production in the presence of sodium ions. We propose that inhibition of mitochondrial K+ transport by Na ions on K+ channel opening may be important for cell protection and ATP synthesis.