Ukr.Biochem.J. 2025; Volume 97, Issue 6, Nov-Dec, pp. 23-32

doi: https://doi.org/10.15407/ubj97.06.023

Identification of different subtypes of K(+) channels in the mitochondria of rat myometrium using K(+) channels modulators

16.12.2025   Uncategorized

M. V. Rudnytska, H. V. Danylovych*, M. R. Pavliuk, Yu. V. Danylovych

Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
*e-mail: danylovychanna@ukr.net

Received: 17 July 2025; Revised: 25 September 2025;
Accepted: 28 November 2025; Available on-line:   23 December 2025

Potassium ions affect Ca2+ transport in mitochondria, the magnitude of the electric potential on the inner mitochondrial membrane, metabolic processes in the matrix, and osmoregulation. The aim of this study was to identify different subtypes of K+ channels in the mitochondria of rat myometrium. Isolated mitochondria were obtained from the myometrium of non-pregnant Wistar rats by differential centrifugation. Potassium ion accumulation was studied by spectrofluorimetry using the K+-sensitive fluorescent probe PBFI-AM. Myometrial mitochondria effectively accumulate potassium ions within the concentration range of 25–150 mM. No increase in PBFI fluorescence was observed when K+ ions were replaced by choline in equimolar concentrations. In the presence of voltage-operated K+ channels inhibitor 4-aminopyridine, Ca2+-dependent K+ channels blockers charybdotoxin or paxilline, mitoKATP channels inhibitors glibenclamide, 5-hydroxydecanoic acid, or 200 μM ATP, a significant decrease in the PBFI fluorescence signal was observed. Conversely, application of Ca2+-dependent K+ channels specific activators NS11021 and NS1619, as well as of mitoKATP-specific activator cromakalim, resulted in increased mitochondrial K+ accumulation. The efficiency of K+ uptake increased further with the addition of 25–100 μM Ca²⁺ in the presence of 4-aminopyridine and ATP. The results obtained indicate the presence of voltage-operated and Ca2+-dependent subtypes of K+ channels, as well as of H+/K+ exchange system in myometrial mitochondria in addition to mitoKATP channels.

Keywords: , , , ,

References:

  1. Laskowski M, Augustynek B, Kulawiak B, Koprowski P, Bednarczyk P, Jarmuszkiewicz W, Szewczyk A. What do we not know about mitochondrial potassium channels? Biochim Biophys Acta. 2016;1857(8):1247-1257. PubMed, CrossRef
  2. Killilea DW, Killilea AN. Mineral requirements for mitochondrial function: A connection to redox balance and cellular differentiation. Free Radic Biol Med. 2022;182:182-191. PubMed, PubMedCentral, CrossRef
  3. Naima J, Ohta Y. Potassium Ions Decrease Mitochondrial Matrix pH: Implications for ATP Production and Reactive Oxygen Species Generation. Int J Mol Sci. 2024;25(2):1233. PubMed, PubMedCentral, CrossRef
  4. Rotko D, Kunz WS, Szewczyk A, Kulawiak B. Signaling pathways targeting mitochondrial potassium channels. Int J Biochem Cell Biol. 2020;125:105792. PubMed, CrossRef
  5. Kulawiak B, Bednarczyk P, Szewczyk A. Multidimensional Regulation of Cardiac Mitochondrial Potassium Channels. Cells. 2021;10(6):1554. PubMed, PubMedCentral, CrossRef
  6. Wray S, Prendergast C. The Myometrium: From Excitation to Contractions and Labour. Adv Exp Med Biol. 2019;1124:233-263. PubMed, CrossRef
  7. Burdyga T, Poul RJ. Chapter 86 ‒ Calcium Homeostasis and Signaling in Smooth Muscle. Muscle. 2012;2:1155-1171. CrossRef
  8. Bock FJ, Tait SWG. Mitochondria as multifaceted regulators of cell death. Nat Rev Mol Cell Biol. 2020;21(2):85-100. PubMed, CrossRef
  9. Alston CL, Rocha MC, Lax NZ, Turnbull DM, Taylor RW. The genetics and pathology of mitochondrial disease. J Pathol. 2017;241(2):236-250. PubMed, PubMedCentral, CrossRef
  10. Dan Dunn J, Alvarez LA, Zhang X, Soldati T. Reactive oxygen species and mitochondria: A nexus of cellular homeostasis. Redox Biol. 2015;6:472-485. PubMed, PubMedCentral, CrossRef
  11. Zhang L, Zheng Y, Xie J, Shi L. Potassium channels and their emerging role in parkinson’s disease. Brain Res Bull. 2020;160:1-7. PubMed, CrossRef
  12. Wang CH, Wei YH. Role of mitochondrial dysfunction and dysregulation of Ca2+ homeostasis in the pathophysiology of insulin resistance and type 2 diabetes. J Biomed Sci. 2017;24(1):70. PubMed, PubMedCentral, CrossRef
  13. Brainard AM, Korovkina VP, England SK. Potassium channels and uterine function. Semin Cell Dev Biol. 2007;18(3):332-339. PubMed, PubMedCentral, CrossRef
  14. Zullino S, Buzzella F, Simoncini T. Nitric oxide and the biology of pregnancy. Vascul Pharmacol. 2018;110:71-74. PubMed, CrossRef
  15. Ulrich C, Quilici DR, Schlauch KA, Buxton IL. The human uterine smooth muscle S-nitrosoproteome fingerprint in pregnancy, labor, and preterm labor. Am J Physiol Cell Physiol. 2013;305(8):C803-C816. PubMed, PubMedCentral, CrossRef
  16. O’Rourke B. Evidence for mitochondrial K+ channels and their role in cardioprotection. Circ Res. 2004;94(4):420-432. PubMed, PubMedCentral, CrossRef
  17. Szewczyk A, Jarmuszkiewicz W, Kunz WS. Mitochondrial potassium channels. IUBMB Life. 2009;61(2):134-143. PubMed, CrossRef
  18. Trombetta-Lima M, Krabbendam IE, Dolga AM. Calcium-activated potassium channels: implications for aging and age-related neurodegeneration. Int J Biochem Cell Biol. 2020;123:105748. PubMed, CrossRef
  19. Garlid KD, Paucek P. Mitochondrial potassium transport: the K(+) cycle. Biochim Biophys Acta. 2003;1606(1-3):23-41. PubMed, CrossRef
  20. Chapa-Dubocq XR, Rodríguez-Graciani KM, Escobales N, Javadov S. Mitochondrial Volume Regulation and Swelling Mechanisms in Cardiomyocytes. Antioxidants (Basel). 2023;12(8):1517. PubMed, PubMedCentral, CrossRef
  21. Aldakkak M, Stowe DF, Cheng Q, Kwok WM, Camara AK. Mitochondrial matrix K+ flux independent of large-conductance Ca2+-activated K+ channel opening. Am J Physiol Cell Physiol. 2010;298(3):C530-C541. PubMed, PubMedCentral, CrossRef
  22. Csonka C, Kupai K, Bencsik P, Görbe A, Pálóczi J, Zvara A, Puskás LG, Csont T, Ferdinandy P. Cholesterol-enriched diet inhibits cardioprotection by ATP-sensitive K+ channel activators cromakalim and diazoxide. Am J Physiol Heart Circ Physiol. 2014;306(3):H405-H413. PubMed, CrossRef
  23. Costa AD, Quinlan CL, Andrukhiv A, West IC, Jabůrek M, Garlid KD. The direct physiological effects of mitoK(ATP) opening on heart mitochondria. Am J Physiol Heart Circ Physiol. 2006;290(1):H406-H415. PubMed, PubMedCentral, CrossRef
  24. Yamada M. Mitochondrial ATP-sensitive K+ channels, protectors of the heart. J Physiol. 2010;588(Pt 2):283-286. PubMed, PubMedCentral, CrossRef
  25. Piwonska M, Wilczek E, Szewczyk A, Wilczynski GM. Differential distribution of Ca2+-activated potassium channel beta4 subunit in rat brain: immunolocalization in neuronal mitochondria. Neuroscience. 2008;153(2):446-460. PubMed, CrossRef
  26. Gulbins E, Sassi N, Grassmè H, Zoratti M, Szabò I. Role of Kv1.3 mitochondrial potassium channel in apoptotic signalling in lymphocytes. Biochim Biophys Acta. 2010;1797(6-7):1251-1259. PubMed, CrossRef
  27. Wrzosek A, Augustynek B, Żochowska M, Szewczyk A. Mitochondrial Potassium Channels as Druggable Targets. Biomolecules. 2020;10(8):1200. PubMed, PubMedCentral, CrossRef
  28. Inoue I, Nagase H, Kishi K, Higuti T. ATP-sensitive K+ channel in the mitochondrial inner membrane. Nature. 1991;352(6332):244-247. PubMed, CrossRef
  29. Kicinska A, Augustynek B, Kulawiak B, Jarmuszkiewicz W, Szewczyk A, Bednarczyk P. A large-conductance calcium-regulated K+ channel in human dermal fibroblast mitochondria. Biochem J. 2016;473(23):4457-4471. PubMed, CrossRef
  30. Szabo I, Zoratti M. Mitochondrial channels: ion fluxes and more. Physiol Rev. 2014;94(2):519-608.
    PubMed, CrossRef
  31. Kravenska Y, Checchetto V, Szabo I. Routes for Potassium Ions across Mitochondrial Membranes: A Biophysical Point of View with Special Focus on the ATP-Sensitive K+ Channel. Biomolecules. 2021;11(8):1172. PubMed, PubMedCentral, CrossRef
  32. Augustynek B, Kunz WS, Szewczyk A. Guide to the Pharmacology of Mitochondrial Potassium Channels. Handb Exp Pharmacol. 2017;240:103-127. PubMed, CrossRef
  33. Vadzyuk OB, Kosterin SO. Mitochondria from rat uterine smooth muscle possess ATP-sensitive potassium channel. Saudi J Biol Sci. 2018;25(3):551-557. PubMed, PubMedCentral, CrossRef
  34. Bradford MM. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal Biochem. 1976;72:248-254. PubMed, CrossRef
  35. Kasner SE, Ganz MB. Regulation of intracellular potassium in mesangial cells: a fluorescence analysis using the dye, PBFI. Am J Physiol. 1992;262(3 Pt 2):F462-F467. PubMed, CrossRef
  36. Garlid KD. Unmasking the mitochondrial K/H exchanger: tetraethylammonium-induced K+-loss. Biochem Biophys Res Commun. 1979;87(3):842-847. PubMed, CrossRef
  37. Smith RC, McClure MC, Smith MA, Abel PW, Bradley ME. The role of voltage-gated potassium channels in the regulation of mouse uterine contractility. Reprod Biol Endocrinol. 2007;5:41. PubMed, PubMedCentral, CrossRef
  38. Paggio A, Checchetto V, Campo A, Menabò R, Di Marco G, Di Lisa F, Szabo I, Rizzuto R, De Stefani D. Identification of an ATP-sensitive potassium channel in mitochondria. Nature. 2019;572(7771):609-613. PubMed, PubMedCentral, CrossRef
  39. Shah DA, Khalil RA. Bioactive factors in uteroplacental and systemic circulation link placental ischemia to generalized vascular dysfunction in hypertensive pregnancy and preeclampsia. Biochem Pharmacol. 2015;95(4):211-226. PubMed, PubMedCentral, CrossRef
  40. Yang W, Cheng Z, Dai H. Calcium concentration response to uterine ischemia: a comparison of uterine fibroid cells and adjacent normal myometrial cells. Eur J Obstet Gynecol Reprod Biol. 2014;174:123-127. PubMed, CrossRef
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