Tag Archives: Mg(2+)
Extramitochondrial ATP modulates Са(2+) signaling in myometrial mitochondria
L. G. Babich*, S. G. Shlykov, A. I. Panchenko, S. O. Kosterin
Department of Muscle Biochemistry, Palladin Institute of Biochemistry,
National Academy of Sciences of Ukraine, Kyiv;
*e-mail: babich@biochem.kiev.ua
Received: 16 September 2025; Revised: 21 October 2025;
Accepted: 30 January 2026; Available on-line: 23 February 2026
It was postulated that mitochondria are sensors and effectors of ATP synthesis. Our results suggest that ATP may play a role as an intracellular signaling molecule. We have shown that the baseline Ca2+ concentration in the mitochondrial matrix increased in the presence of ATP or MgATP in the incubation media of isolated mitochondria. Activation or inhibition of both the respiration and Ca2+ uniporter activity, as well as the removal of Mg2+ from the incubation medium, or addition of A438079, an antagonist of plasma membrane P2X7 receptors, followed by the addition of ATP did not affect the ATP-induced increase of matrix baseline Ca2+ concentration. These results showed that extramitochondrial ATP modulates Ca2+ signaling in mitochondria independently of the Ca2+ uniporter and the respiratory chain activity. In the presence of UTP or MgUTP instead of ATP or MgATP, an increase of the matrix baseline Ca2+ concentration was not observed indicating that the studied effects are selective for ATP.
Сalix[4]arene chalcone amides effects on myometrium mitochondria
S. G. Shlykov1, A. M. Kushnarova-Vakal1, A. V. Sylenko1,
L. G. Babich1, О. Yu. Chunikhin1, O. A. Yesypenko2,
V. I. Kalchenko2, S. O. Kosterin1
1Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: sshlykov@biochem.kiev.ua;
2Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Kyiv
Received: 19 November 2018; Accepted: 14 March 2019
Mitochondria are a key player in a wide range of the most important functions of the cell. Calixarenes are supramolecular compounds that have been widely used in bioorganic chemistry and biochemistry. The aim of this work was to study the effects of calix[4]arenes with two (С-1012, С-1021), three (С-1023, С-1024) and four (С-1011) chalcone amide groups on the myometrial mitochondria membranes polarization, Ca2+ concentration in the matrix of these organelles ([Ca2+]m ) and on the average hydrodynamic diameter of mitochondria. It was shown that permeabilized myometrium cells incubation with calix[4]arenes containing two or more chalcone amide groups, was accompanied by an increased level of myometrial mitochondria membranes polarization. All studied calix[4]arenes increased [Ca2+]m values in the absence and in the presence of exogenous Ca2+. The values of [Ca2+]m in the absence of exogenous Ca2+ were higher at mitochondria incubation in Mg2+-containing, than in Mg2+,ATP-containing medium. Incubation of isolated mitochondria with the studied calix[4]arenes resulted in changes of mitochondria volume: at incubation with С-1012, С-1021, C-1023 the average hydrodynamic diameter was decreased, while with С-1011 it was increased. Thus, we have shown that a short-term (5 min) incubation of mitochondria in the presence of 10 µM calix[4]arenes, which contain from two to four chalcone amide groups, increased the level of mitochondria membranes polarization, ionized Ca concentration in the matrix and had different effects on the mitochondrial volume.
Ca(2+)-dependent regulation of the Ca(2+) concentration in the myometrium mitochondria. II. Ca(2+) effects on mitochondria membranes polarization and [Ca(2+)](m)
L. G. Babich, S. G. ShlykoV, A. M. Kushnarova, S. O. Kosterin
Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: babich@biochem.kiev.ua
It is known that Ca2+ accumulation in the mitochondria undergoes complex regulation by Ca2+ itself. But the mechanisms of such regulation are still discussed. In this paper we have shown that Ca ions directly or indirectly regulate the level of myometrium mitochondria membranes polarization. The additions of 100 µM Ca2+ were accompanied by depolarization of the mitochondria membranes. The following experiments were designed to study the impact of Ca2+ on the myometrium mitochondria [Ca2+]m. Isolated myometrium mitochondria were preincubated without or with 10 μM Са2+ followed by 100 μM Са2+ addition. Experiments were conducted in three mediums: without ATP and Mg2+ (0-medium), in the presence of 3 mM Mg2+ (Mg-medium) and 3 mM Mg2+ + 3 mM ATP (Mg,ATP-medium). It was shown that the effects of 10 μM Са2+ addition were different in different mediums, namely in 0- and Mg-medium the [Ca2+]m values increased, whereas in Mg,ATP-medium statistically reliable changes were not registered. Preincubation of mitochondria with 10 μM Са2+ did not affect the [Ca2+]m value after the addition of 100 μM Са2+. The [Ca2+]m values after 100 μM Са2+ addition were the same in 0- and Mg,ATP-mediums and somewhat lower in Mg-medium. Preliminary incubation of mitochondria with 10 μM Са2+ in 0- and Mg-mediums reduced changes of Fluo 4 normalized fluorescence values that were induced by 100 μM Са2+ additions, but in Mg,ATP-medium such differences were not recorded. It is concluded that Са2+ exchange in myometrium mitochondria is regulated by the concentration of Ca ions as in the external medium, so in the matrix of mitochondria. The medium composition had a significant impact on the [Са2+]m values in the absence of exogenous cation. It is suggested that light increase of [Са2+]m before the addition of 100 μM Са2+ may have a positive effect on the functional activity of the mitochondria.