Effect of Potential-Dependent Potassium Uptake on Calcium Accumulation in Rat Brain Mitochondria

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O. V. Akopova^*, L. I. Kolchinskaya, V. I. Nosar, V. A. Bouryi, I. N. Mankovskaya, and V. F. Sagach

Bogomolets Institute of Physiology, National Academy of Sciences of Ukraine, ul. Bogomoltsa 4, Kiev-24, Ukraine; E-mail: a-dubensky@mail.ru

^* To whom correspondence should be addressed.

Received June 13, 2012; Revision received September 19, 2012

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The effect of potential-dependent potassium uptake at 0-120 mM K⁺ on matrix Ca²⁺ accumulation in rat brain mitochondria was studied. An increase in oxygen consumption and proton extrusion rates as well as increase in matrix pH with increase in K⁺ content in the medium was observed due to K⁺ uptake into the mitochondria. The accumulation of Ca²⁺ was shown to depend on K⁺ concentration in the medium. At K⁺ concentration ≤30 mM, Ca²⁺ uptake is decreased due to K⁺-induced membrane depolarization, whereas at higher K⁺ concentrations, up to 120 mM K⁺, Ca²⁺ uptake is increased in spite of membrane depolarization caused by matrix alkalization due to K⁺ uptake. Mitochondrial K⁺_ATP-channel blockers (glibenclamide and 5-hydroxydecanoic acid) diminish K⁺ uptake as well as K⁺-induced depolarization and matrix alkalization, which results in attenuation of the potassium-induced effects on matrix Ca²⁺ uptake, i.e. increase in Ca²⁺ uptake at low K⁺ content in the medium due to the smaller membrane depolarization and decrease in Ca²⁺ uptake at high potassium concentrations because of restricted rise in matrix pH. The results show the importance of potential-dependent potassium uptake, and especially the K⁺_ATP channel, in the regulation of calcium accumulation in rat brain mitochondria.

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KEY WORDS: brain, mitochondria, Ca²⁺ uptake, K⁺ uptake, K⁺_ATP channel

DOI: 10.1134/S0006297913010100

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