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Ágoston M, Kohajda Z, Virág L, Baláti B, Nagy N, Lengyel C, Bitay M, Bogáts G, Vereckei A, Papp JG, Varró A, Jost N. A Comparative Study of the Rapid (I Kr) and Slow (I Ks) Delayed Rectifier Potassium Currents in Undiseased Human, Dog, Rabbit, and Guinea Pig Cardiac Ventricular Preparations. Pharmaceuticals (Basel) 2024; 17:1091. [PMID: 39204196 PMCID: PMC11357539 DOI: 10.3390/ph17081091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2024] [Revised: 07/24/2024] [Accepted: 08/09/2024] [Indexed: 09/03/2024] Open
Abstract
To understand the large inter-species variations in drug effects on repolarization, the properties of the rapid (IKr) and the slow (IKs) components of the delayed rectifier potassium currents were compared in myocytes isolated from undiseased human donor (HM), dog (DM), rabbit (RM) and guinea pig (GM) ventricles by applying the patch clamp and conventional microelectrode techniques at 37 °C. The amplitude of the E-4031-sensitive IKr tail current measured at -40 mV after a 1 s long test pulse of 20 mV, which was very similar in HM and DM but significant larger in RM and GM. The L-735,821-sensitive IKs tail current was considerably larger in GM than in RM. In HM, the IKs tail was even smaller than in DM. At 30 mV, the IKr component was activated extremely rapidly and monoexponentially in each studied species. The deactivation of the IKr component in HM, DM, and RM measured at -40 mV. After a 30 mV pulse, it was slow and biexponential, while in GM, the IKr tail current was best fitted triexponentially. At 30 mV, the IKs component activated slowly and had an apparent monoxponential time course in HM, DM, and RM. In contrast, in GM, the activation was clearly biexponential. In HM, DM, and RM, IKs component deactivation measured at -40 mV was fast and monoexponential, while in GM, in addition to the fast component, another slower component was also revealed. These results suggest that the IK in HM resembles that measured in DM and RM and considerably differs from that observed in GM. These findings suggest that the dog and rabbit are more appropriate species than the guinea pig for preclinical evaluation of new potential drugs expected to affect cardiac repolarization.
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Affiliation(s)
- Márta Ágoston
- Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical School, University of Szeged, P.O. Box 427, 6701 Szeged, Hungary
| | - Zsófia Kohajda
- HUN-REN-SZTE Research Group for Cardiovascular Pharmacology, 6701 Szeged, Hungary
| | - László Virág
- Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical School, University of Szeged, P.O. Box 427, 6701 Szeged, Hungary
- Interdisciplinary Research and Development and Innovation Centre of Excellence, University of Szeged, 6720 Szeged, Hungary
| | - Beáta Baláti
- Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical School, University of Szeged, P.O. Box 427, 6701 Szeged, Hungary
| | - Norbert Nagy
- Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical School, University of Szeged, P.O. Box 427, 6701 Szeged, Hungary
- HUN-REN-SZTE Research Group for Cardiovascular Pharmacology, 6701 Szeged, Hungary
| | - Csaba Lengyel
- Department of Medicine, Albert Szent-Györgyi Medical School, University of Szeged, 6720 Szeged, Hungary
| | - Miklós Bitay
- Department of Cardiac Surgery, Albert Szent-Györgyi Medical School, University of Szeged, 6742 Szeged, Hungary
| | - Gábor Bogáts
- Department of Cardiac Surgery, Albert Szent-Györgyi Medical School, University of Szeged, 6742 Szeged, Hungary
| | - András Vereckei
- Department of Internal Medicine and Haematology, Semmelweis University, 1088 Budapest, Hungary
| | - Julius Gy. Papp
- Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical School, University of Szeged, P.O. Box 427, 6701 Szeged, Hungary
- HUN-REN-SZTE Research Group for Cardiovascular Pharmacology, 6701 Szeged, Hungary
| | - András Varró
- Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical School, University of Szeged, P.O. Box 427, 6701 Szeged, Hungary
- HUN-REN-SZTE Research Group for Cardiovascular Pharmacology, 6701 Szeged, Hungary
- Interdisciplinary Research and Development and Innovation Centre of Excellence, University of Szeged, 6720 Szeged, Hungary
| | - Norbert Jost
- Department of Pharmacology and Pharmacotherapy, Albert Szent-Györgyi Medical School, University of Szeged, P.O. Box 427, 6701 Szeged, Hungary
- HUN-REN-SZTE Research Group for Cardiovascular Pharmacology, 6701 Szeged, Hungary
- Interdisciplinary Research and Development and Innovation Centre of Excellence, University of Szeged, 6720 Szeged, Hungary
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Lu TL, Lu TJ, Wu SN. Inhibitory Effective Perturbations of Cilobradine (DK-AH269), A Blocker of HCN Channels, on the Amplitude and Gating of Both Hyperpolarization-Activated Cation and Delayed-Rectifier Potassium Currents. Int J Mol Sci 2020; 21:ijms21072416. [PMID: 32244431 PMCID: PMC7177279 DOI: 10.3390/ijms21072416] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 03/17/2020] [Accepted: 03/28/2020] [Indexed: 12/19/2022] Open
Abstract
Cilobradine (CIL, DK-AH269), an inhibitor of hyperpolarization-activated cation current (Ih), has been observed to possess pro-arrhythmic properties. Whether and how CIL is capable of perturbing different types of membrane ionic currents existing in electrically excitable cells, however, is incompletely understood. In this study, we intended to examine possible modifications by it or other structurally similar compounds of ionic currents in pituitary tumor (GH3) cells and in heart-derived H9c2 cells. The standard whole-cell voltage-clamp technique was performed to examine the effect of CIL on ionic currents. GH3-cell exposure to CIL suppressed the density of hyperpolarization-evoked Ih in a concentration-dependent manner with an effective IC50 of 3.38 μM. Apart from its increase in the activation time constant of Ih during long-lasting hyperpolarization, the presence of CIL (3 μM) distinctly shifted the steady-state activation curve of Ih triggered by a 2-s conditioning pulse to a hyperpolarizing direction by 10 mV. As the impedance-frequency relation of Ih was studied, its presence raised the impedance magnitude at the resonance frequency induced by chirp voltage. CIL also suppressed delayed-rectifier K+ current (IK(DR)) followed by the accelerated inactivation time course of this current, with effective IC50 (measured at late IK(DR)) or KD value of 3.54 or 3.77 μM, respectively. As the CIL concentration increased 1 to 3 μM, the inactivation curve of IK(DR) elicited by 1- or 10-s conditioning pulses was shifted to a hyperpolarizing potential by approximately 10 mV, and the recovery of IK(DR) inactivation during its presence was prolonged. The peak Na+ current (INa) during brief depolarization was resistant to being sensitive to the presence of CIL, yet to be either decreased by subsequent addition of A-803467 or enhanced by that of tefluthrin. In cardiac H9c2 cells, unlike the CIL effect, the addition of either ivabradine or zatebradine mildly led to a lowering in IK(DR) amplitude with no conceivable change in the inactivation time course of the current. Taken together, the compound like CIL, which was tailored to block hyperpolarization-activated cation (HCN) channels effectively, was also capable of altering the amplitude and gating of IK(DR), thereby influencing the functional activities of electrically excitable cells, such as GH3 cells.
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Affiliation(s)
- Te-Ling Lu
- School of Pharmacy, China Medical University, Taichung 40402, Taiwan;
| | - Te-Jung Lu
- Department of Medical Laboratory Science and Biotechnology, Chung Hwa University of Medical Technology, Tainan 71703, Taiwan;
| | - Sheng-Nan Wu
- Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan 70101, Taiwan
- Department of Physiology, National Cheng Kung University Medical College, Tainan 70101, Taiwan
- Department of Medical Research, China Medical University Hospital, China Medical University, Taichung 40402, Taiwan
- Correspondence:
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Chang WT, Lo YC, Gao ZH, Wu SN. Evidence for the Capability of Roxadustat (FG-4592), an Oral HIF Prolyl-Hydroxylase Inhibitor, to Perturb Membrane Ionic Currents: An Unidentified yet Important Action. Int J Mol Sci 2019; 20:ijms20236027. [PMID: 31795416 PMCID: PMC6928729 DOI: 10.3390/ijms20236027] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 11/18/2019] [Accepted: 11/25/2019] [Indexed: 12/13/2022] Open
Abstract
Roxadustat (FG-4592), an analog of 2-oxoglutarate, is an orally-administered, heterocyclic small molecule known to be an inhibitor of hypoxia inducible factor (HIF) prolyl hydroxylase. However, none of the studies have thus far thoroughly investigated its possible perturbations on membrane ion currents in endocrine or heart cells. In our studies, the whole-cell current recordings of the patch-clamp technique showed that the presence of roxadustat effectively and differentially suppressed the peak and late components of IK(DR) amplitude in response to membrane depolarization in pituitary tumor (GH3) cells with an IC50 value of 5.71 and 1.32 μM, respectively. The current inactivation of IK(DR) elicited by 10-sec membrane depolarization became raised in the presence of roxadustatt. When cells were exposed to either CoCl2 or deferoxamine (DFO), the IK(DR) elicited by membrane depolarization was not modified; however, nonactin, a K+-selective ionophore, in continued presence of roxadustat, attenuated roxadustat-mediated inhibition of the amplitude. The steady-state inactivation of IK(DR) could be constructed in the presence of roxadustat. Recovery of IK(DR) block by roxadustat (3 and 10 μM) could be fitted by a single exponential with 382 and 523 msec, respectively. The roxadustat addition slightly suppressed erg-mediated K+ or hyperpolarization-activated cation currents. This drug also decreased the peak amplitude of voltage-gated Na+ current with a slowing in inactivation rate of the current. Likewise, in H9c2 heart-derived cells, the addition of roxadustat suppressed IK(DR) amplitude in combination with the shortening in inactivation time course of the current. In high glucose-treated H9c2 cells, roxadustat-mediated inhibition of IK(DR) remained unchanged. Collectively, despite its suppression of HIF prolyl hydroxylase, inhibitory actions of roxadustat on different types of ionic currents possibly in a non-genomic fashion might provide another yet unidentified mechanism through which cellular functions are seriously perturbed, if similar findings occur in vivo.
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Affiliation(s)
- Wei-Ting Chang
- Division of Cardiovascular Medicine, Chi-Mei Medical Center, Tainan 71004 Taiwan;
- Department of Biotechnology, Southern Taiwan University of Science and Technology, Tainan 71004, Taiwan
- Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan 70101, Taiwan
| | - Yi-Ching Lo
- Department of Pharmacology, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan;
| | - Zi-Han Gao
- Department of Physiology, National Cheng Kung University Medical College, Tainan 70101, Taiwan;
| | - Sheng-Nan Wu
- Department of Physiology, National Cheng Kung University Medical College, Tainan 70101, Taiwan;
- Institute of Basic Medical Sciences, National Cheng Kung University Medical College, Tainan 70101, Taiwan
- Department of Basic Medical Sciences, China Medical University Hospital, Taichung 40402, Taiwan
- Correspondence: ; Tel.: +886-6-2353535-5334/886-6-2362780
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Kuo PC, Yang CJ, Lee YC, Chen PC, Liu YC, Wu SN. The comprehensive electrophysiological study of curcuminoids on delayed-rectifier K + currents in insulin-secreting cells. Eur J Pharmacol 2018; 819:233-241. [DOI: 10.1016/j.ejphar.2017.12.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 12/04/2017] [Accepted: 12/04/2017] [Indexed: 12/16/2022]
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Haick JM, Byron KL. Novel treatment strategies for smooth muscle disorders: Targeting Kv7 potassium channels. Pharmacol Ther 2016; 165:14-25. [PMID: 27179745 DOI: 10.1016/j.pharmthera.2016.05.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Smooth muscle cells provide crucial contractile functions in visceral, vascular, and lung tissues. The contractile state of smooth muscle is largely determined by their electrical excitability, which is in turn influenced by the activity of potassium channels. The activity of potassium channels sustains smooth muscle cell membrane hyperpolarization, reducing cellular excitability and thereby promoting smooth muscle relaxation. Research over the past decade has indicated an important role for Kv7 (KCNQ) voltage-gated potassium channels in the regulation of the excitability of smooth muscle cells. Expression of multiple Kv7 channel subtypes has been demonstrated in smooth muscle cells from viscera (gastrointestinal, bladder, myometrial), from the systemic and pulmonary vasculature, and from the airways of the lung, from multiple species, including humans. A number of clinically used drugs, some of which were developed to target Kv7 channels in other tissues, have been found to exert robust effects on smooth muscle Kv7 channels. Functional studies have indicated that Kv7 channel activators and inhibitors have the ability to relax and contact smooth muscle preparations, respectively, suggesting a wide range of novel applications for the pharmacological tool set. This review summarizes recent findings regarding the physiological functions of Kv7 channels in smooth muscle, and highlights potential therapeutic applications based on pharmacological targeting of smooth muscle Kv7 channels throughout the body.
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Affiliation(s)
- Jennifer M Haick
- Department of Molecular Pharmacology & Therapeutics, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA
| | - Kenneth L Byron
- Department of Molecular Pharmacology & Therapeutics, Stritch School of Medicine, Loyola University Chicago, Maywood, IL, USA.
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Hansen A, Eder A, Bönstrup M, Flato M, Mewe M, Schaaf S, Aksehirlioglu B, Schwoerer AP, Schwörer A, Uebeler J, Eschenhagen T. Development of a drug screening platform based on engineered heart tissue. Circ Res 2010; 107:35-44. [PMID: 20448218 DOI: 10.1161/circresaha.109.211458] [Citation(s) in RCA: 342] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE Tissue engineering may provide advanced in vitro models for drug testing and, in combination with recent induced pluripotent stem cell technology, disease modeling, but available techniques are unsuitable for higher throughput. OBJECTIVE Here, we present a new miniaturized and automated method based on engineered heart tissue (EHT). METHODS AND RESULTS Neonatal rat heart cells are mixed with fibrinogen/Matrigel plus thrombin and pipetted into rectangular casting molds in which two flexible silicone posts are positioned from above. Contractile activity is monitored video-optically by a camera and evaluated by a custom-made software program. Fibrin-based mini-EHTs (FBMEs) (150 microL, 600 000 cells) were transferred from molds to a standard 24-well plate two hours after casting. Over time FBMEs condensed from a 12x3x3 mm gel to a muscle strip of 8 mm length and, depending on conditions, 0.2 to 1.3 mm diameter. After 8 to 10 days, FBMEs started to rhythmically deflect the posts. Post properties and the extent of post deflection allowed calculation of rate, force (0.1 to 0.3 mN), and kinetics which was validated in organ baths experiments. FBMEs exhibited a well-developed, longitudinally aligned actinin-positive cardiac muscle network and lectin-positive vascular structures interspersed homogeneously throughout the construct. Analysis of a large series of FBME (n=192) revealed high yield and reproducibility and stability for weeks. Chromanol, quinidine, and erythromycin exerted concentration-dependent increases in relaxation time, doxorubicin decreases in contractile force. CONCLUSIONS We developed a simple technique to construct large series of EHT and automatically evaluate contractile activity. The method shall be useful for drug screening and disease modeling.
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Affiliation(s)
- Arne Hansen
- Department of Experimental and Clinical Pharmacology and Toxicology, Cardiovascular Research Center, University Medical Center Hamburg-Eppendorf, Germany
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Chen BS, Peng H, Wu SN. Dexmedetomidine, an α2-adrenergic agonist, inhibits neuronal delayed-rectifier potassium current and sodium current. Br J Anaesth 2009; 103:244-54. [DOI: 10.1093/bja/aep107] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Wang YJ, Chen BS, Lin MW, Lin AA, Peng H, Sung RJ, Wu SN. Time-Dependent Block of Ultrarapid-Delayed Rectifier K+ Currents by Aconitine, a Potent Cardiotoxin, in Heart-Derived H9c2 Myoblasts and in Neonatal Rat Ventricular Myocytes. Toxicol Sci 2008; 106:454-63. [DOI: 10.1093/toxsci/kfn189] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
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The mechanisms of propofol-induced block on ion currents in differentiated H9c2 cardiac cells. Eur J Pharmacol 2008; 590:93-8. [DOI: 10.1016/j.ejphar.2008.05.040] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2008] [Revised: 05/09/2008] [Accepted: 05/22/2008] [Indexed: 11/20/2022]
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Wang YJ, Sung RJ, Lin MW, Wu SN. Contribution of BKCa-Channel Activity in Human Cardiac Fibroblasts to Electrical Coupling of Cardiomyocytes-Fibroblasts. J Membr Biol 2007; 213:175-85. [PMID: 17483867 DOI: 10.1007/s00232-007-0027-8] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2006] [Revised: 10/16/2006] [Indexed: 01/30/2023]
Abstract
Cardiac fibroblasts are involved in the maintenance of myocardial tissue structure. However, little is known about ion currents in human cardiac fibroblasts. It has been recently reported that cardiac fibroblasts can interact electrically with cardiomyocytes through gap junctions. Ca(2+)-activated K(+) currents (I (K[Ca])) of cultured human cardiac fibroblasts were characterized in this study. In whole-cell configuration, depolarizing pulses evoked I (K(Ca)) in an outward rectification in these cells, the amplitude of which was suppressed by paxilline (1 microM: ) or iberiotoxin (200 nM: ). A large-conductance, Ca(2+)-activated K(+) (BK(Ca)) channel with single-channel conductance of 162 +/- 8 pS was also observed in human cardiac fibroblasts. Western blot analysis revealed the presence of alpha-subunit of BK(Ca) channels. The dynamic Luo-Rudy model was applied to predict cell behavior during direct electrical coupling of cardiomyocytes and cardiac fibroblasts. In the simulation, electrically coupled cardiac fibroblasts also exhibited action potential; however, they were electrically inert with no gap-junctional coupling. The simulation predicts that changes in gap junction coupling conductance can influence the configuration of cardiac action potential and cardiomyocyte excitability. I (k(Ca)) can be elicited by simulated action potential waveforms of cardiac fibroblasts when they are electrically coupled to cardiomyocytes. This study demonstrates that a BK(Ca) channel is functionally expressed in human cardiac fibroblasts. The activity of these BK(Ca) channels present in human cardiac fibroblasts may contribute to the functional activities of heart cells through transfer of electrical signals between these two cell types.
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Affiliation(s)
- Ya-Jean Wang
- Institute of Basic Medical Sciences, National Cheng Kung University Medical College, No. 1, University Road, Tainan, 701, Taiwan
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Wu SN, Chang HD, Sung RJ. Cocaine-induced inhibition of ATP-sensitive K+ channels in rat ventricular myocytes and in heart-derived H9c2 cells. Basic Clin Pharmacol Toxicol 2006; 98:510-7. [PMID: 16635111 DOI: 10.1111/j.1742-7843.2006.pto_354.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Cocaine use may cause coronary artery spasm and acute myocardial ischaemia/infarction. However, its effects on ATP-sensitive K+ (KATP) channel, an ion channel responsible for ischaemic preconditioning, remain unknown. In isolated rat ventricular myocytes with whole-cell experiments, cocaine can reverse action potential shortening and increased K+ current caused by the openers of ATP-sensitive K+ (KATP) channels. In inside-out patches, cocaine applied to intracellular surface suppressed KATP-channel activity in a concentration-dependent manner with an IC50 value of 9.2 microM; however, it did not modify the single-channel conductance of this channel. The change in the kinetic behaviour of KATP channels caused by cocaine is primarily the result of an increase in mean closed time and a decrease in mean open time. Cocaine-induced inhibition of KATP channels is independent of change in intracellular ATP concentrations. In heart-derived H9c2 cells, cocaine is also capable of suppressing KATP-channel activity. The present study provides evidence that cocaine can produce a depressant action on KATP channels in cardiac myocytes, and thus disturb ischaemic preconditioning in clinical settings.
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Affiliation(s)
- Sheng-Nan Wu
- Department of Physiology, National Cheng Kung University Hospital, Tainan, Taiwan
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