Tag Archives: Na+
Thiacalix[4]arene С-1193 – a promising inhibitor of the sodium pump in the uterine smooth muscle cells
O. V. Maliuk1*, T. O. Veklich1, O. V. Tsymbalyuk2, O. V. Bevza1,
S. O. Cherenok3, A. I. Selikhova3, V. I. Kalchenko3, S. O. Kosterin1
1Palladin Institute of Biochemistry, National Academy of Sciences
of Ukraine, Kyiv, Ukraine;
*e-mail: sanya2000ua@gmail.com;
2Educational and Scientific Institute of High Technologies,
Taras Shevchenko National University of Kyiv, Kyiv, Ukraine;
3Institute of Organic Chemistry, National Academy of Sciences of Ukraine, Kyiv, Ukraine
Received: 29 May 2025; Revised: 18 July 2025;
Accepted: 12 September 2025; Available on-line: 17 September2025
Thiacalix[4]arene C-1193 (25,27-dibutoxythiacalix[4]arene-bis-hydroxymethylphosphonic acid) was shown to inhibit the activity of Na+,K+-ATPase with a high efficiency (І0.5 = 42.1 ± 0.6 nM) with no effect on the activity of Mg2+-ATPase, Са2+-ATPase and Са2+,Mg2+-ATPase in the plasma membrane fraction of rat uterine smooth muscle cells. The kinetic regularities of the C-1193 inhibitory effect on Na+,K+-ATPase activity were investigated. It was demonstrated that C-1193 increased the enzyme activation constant by Na+ but not by K+ ions. The contractile activity of the rat uterine horns was investigated by tenzometric methods with the use of longitudinal uterine smooth muscle strips with intact endometrium. С-1193 induced a considerable increase in the amplitude of the acetylcholine-induced contractions as well as the maximal velocity of the contraction and relaxation phases. No effect of С-1193 on contractive activity induced by the selective agonist of М3-cholinoreceptors cevimeline was observed. The results of computer simulation showed that С-1193inhibitory effect must be related to the cooperative action of methylene bisphosphonate fragments on the upper rim of the calixarene platform, and the linker sulfur atoms of calixarene “cup” on the Na+,K+-ATPase macrostructure.
Influence of Tl(+) on the Ca(2+) and Na(+) movement across rat neonatal cardiomyocytes and rat heart mitochondria membranes
S. M. Korotkov, V. P. Nesterov, G. B. Belostotskaya,
I. V. Brailovskaya, A. V. Novozhilov, C. V. Sobol
Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences, St. Petersburg, Russian Federation;
e-mail: korotkov@SK1645.spb.edu
Received: 05 September 2019; Accepted: 29 November 2019
Thallium is known to produce one of the most complex and serious patterns of toxicity, involving a wide range of human organs and tissues. The toxic impact on biologic organisms is linked especially to the ability of Tl+ to disturb calcium homeostasis and to permeate easily the inner mitochondrial membrane (IMM). The aim of this work was to study the effects of Tl+ on intracellular Ca2+ dynamics in rat neonatal cardiomyocytes as well as on sodium penetrability of the IMM and Tl+-induced mitochondrial permeability transition pore (MPTP) opening in isolated Ca2+-loaded rat heart mitochondria (RHM). The use of the fluorescent calcium indicator Fura 2 AM showed that Tl+ induced calcium influx across the plasmatic membrane, resulting in calcium ([Ca2+]i) increase in the cytoplasm. This increase was even more pronounced in experiments with accelerating of Tl+-transmembrane fluxes by nonactin. It was nevertheless abolished by the removal of extracellular Ca2+ ions, but was not inhibited by a calcium-channel blocker (nifedipine). Tl+ did not release calcium from the intracellular stores. Tl+ potentiated sodium permeability of the IMM because swelling of nonenergized RHM in medium containing TlNO3 and NaNO3 was enhanced at high Tl+ concentration. The calcium load of RHM induced MPTP opening which was accompanied by the increase of the swelling as well as the decrease of the inner membrane potential and of state 40 (basal) and state 3UDNP (2,4-dinitrophenol-uncoupled) respiration. These effects of Tl+ were suppressed by MPTP inhibitors (cyclosporine A, ADP and n-ethylmaleimide). The data obtained showed that Tl+-stimulated influx of extracellular calcium into cardiomyocytes could cause calcium and sodium RHM overload, which lead to the MPTP opening, thus determining the sensitivity of heart muscle to thallium intoxication.