XXII. BIOCHEMICKÝ ZJAZD - Jesseniova lekárska fakulta

Lectures
EffECT of aDENINE NUCLEOTIDES aND Mg 2+ IONS ON
MITOCHONDrial CHLOrIDE CHaNNELS
Viera Kominková, Zuzana Tomášková, Ľubica Máleková and Karol Ondriaš
Institute of molecular physiology and genetics, Slovak Academy of Sciences,
Bratislava, Slovak Republic
Chloride channels are involved in many physiological and pathological processes such
as the apoptosis, stress, reperfusion injury or cardioprotection. The cells in ischemic
tissues are depleted of oxygen and lose their capacity for ATP production. Due to this
energy deprivation, destructive processes are activated which lead to cell injury or death.
Molecular mechanisms of these processes are still not fully understood. The aim of our
work was to study the possible role of mitochondrial chloride channels in these processes.
We report the effect of adenine nucleotides (ATP, ADP and AMP-PNP) and Mg 2+ on the
activity of mitochondrial chloride channels. Submitochondrial vesicles isolated from
rat heart were incorporated into bilayer lipid membrane and single chloride channel
currents were measured. We found that ATP inhibited chloride channels and affected
both kinetics and current amplitude. This inhibitory effect was not dependent on phosphorylation
of the channel. Furthermore, ADP did not affect the channel activity but
only decreased the current amplitude. When the effect of ATP was studied in Mg 2+ free
solutions, a hyperbolic current-voltage relationship was observed after addition of ATP.
Addition of MgCl 2
(up to 5mmol/L) partially relieved this effect of ATP.
ATP, within the range of physiological concentrations, inhibits the mitochondrial chloride
channels, which invokes a hypothesis that these channels have a role during pathological
processes connected with ATP depletion.
Acknowledgements: This work was supported by VEGA 2/0150/10 and VVCE-0064-07.
XXII. Biochemistry Congress, Martin
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