STUDIES OF INTERACTION OF INTRACELLULAR SIGNALLING AND METABOLIC PATHWAYS
UNDER INHIBITION OF MITOCHONDRIAL ACONITASE WITH FLUOROACETATE
V. P. Zinchenko,1 N. V. Goncharov,2, * V. V. Teplova,3
V. A. Kasymov,1 O. I. Petrova,1 A. V. Berezhnov,1
E. V. Senchenkov,2 I. V. Mindukshev,4 R. O. Jenkins,5
A. S. Radilov 2
1 Institute of Cell Biophysics RAS, Pushchino,
2 Research Institute of Hygiene, Occupational Pathology and Human Ecology, St. Petersburg,
3 Institute of Theoretical and Experimental Biophysics RAS, Pushchino,
4 I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry RAS, St. Petersburg,
and 5 School of Allied Health Sciences, De Montfort University, Leicester, UK;
* e-mail: nvgoncharov@mail.ru
Mitochondrial aconitase has been shown to be inactivated by a spectrum of substances or critical states.
Fluoroacetate (FA) is the most known toxic agent inhibiting aconitase. The biochemistry of toxic action of FA is
rather well understood, though no effective therapy has been proposed for the past six decades. In order to reveal
novel approaches for possible antidotes to be developed, experiments were performed with rat liver mitochondria,
Ehrlich ascite tumor cells and cardiomyocytes, exposed to FA or fluorocitrate in vitro. The effect of FA
developed at much higher concentrations in comparison with fluorocitrate and was dependent upon respiratory
substrates in experiments with mitochondria: with pyruvate, FA induced a slow oxidation and/or leak of pyridine
nucleotides and inhibition of respiration. Oxidation of pyridine nucleotides was prevented by incubation of
mitochondria with cyclosporin A. Studies of the pyridine nucleotides level and calcium response generated in
Ehrlich ascite tumor cells under activation with ATP also revealed a loss of pyridine nucleotides from mitochondria
resulting in a shift in the balance of mitochondrial and cytosolic NAD(P)H under exposure to FA. An increase
of cytosolic [Ca2+] was observed in the cell lines exposed to FA and is explained by activation of plasma
membrane calcium channels; this mechanism, could have an impact on amplitude and rate of Ca2+ waves in
cardiomyocytes. Highlighting the reciprocal relationship between intracellular pyridine nucleotides and calcium
balance, we discuss metabolic pathway modulation in the context of probable development of an effective therapy
for FA poisoning and other inhibitors of aconitase.
Key words: fluoroacetate, intracellular calcium, pyridine nucleotides, mitochondria,
membrane potential
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