1
|
Tian X, Gu L, Zeng F, Liu X, Zhou Y, Dou Y, Han J, Zhao Y, Zhang Y, Luo Q, Wang F. Strophanthidin Induces Apoptosis of Human Lung Adenocarcinoma Cells by Promoting TRAIL-DR5 Signaling. Molecules 2024; 29:877. [PMID: 38398629 PMCID: PMC10892344 DOI: 10.3390/molecules29040877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2024] [Revised: 02/08/2024] [Accepted: 02/08/2024] [Indexed: 02/25/2024] Open
Abstract
Strophanthidin (SPTD), one of the cardiac glycosides, is refined from traditional Chinese medicines such as Semen Lepidii and Antiaris toxicaria, and was initially used for the treatment of heart failure disease in clinic. Recently, SPTD has been shown to be a potential anticancer agent, but the underlying mechanism of action is poorly understood. Herein, we explored the molecular mechanism by which SPTD exerts anticancer effects in A549 human lung adenocarcinoma cells by means of mass spectrometry-based quantitative proteomics in combination with bioinformatics analysis. We revealed that SPTD promoted the expression of tumor necrosis factor (TNF)-related apoptosis-inducing ligand receptor 2 (TRAIL-R2, or DR5) in A549 cells to activate caspase 3/6/8, in particular caspase 3. Consequently, the activated caspases elevated the expression level of apoptotic chromatin condensation inducer in the nucleus (ACIN1) and prelamin-A/C (LMNA), ultimately inducing apoptosis via cooperation with the SPTD-induced overexpressed barrier-to-autointegration factor 1 (Banf1). Moreover, the SPTD-induced DEPs interacted with each other to downregulate the p38 MAPK/ERK signaling, contributing to the SPTD inhibition of the growth of A549 cells. Additionally, the downregulation of collagen COL1A5 by SPTD was another anticancer benefit of SPTD through the modulation of the cell microenvironment.
Collapse
Affiliation(s)
- Xiao Tian
- College of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan 250355, China;
- Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, National Centre for Mass Spectrometry in Beijing, CAS Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China; (L.G.); (X.L.); (Y.Z.); (Y.D.); (J.H.); (Y.Z.); (Y.Z.)
| | - Liangzhen Gu
- Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, National Centre for Mass Spectrometry in Beijing, CAS Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China; (L.G.); (X.L.); (Y.Z.); (Y.D.); (J.H.); (Y.Z.); (Y.Z.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fangang Zeng
- School of Environment of Natural Resources, Remin University of China, Beijing 100875, China;
| | - Xingkai Liu
- Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, National Centre for Mass Spectrometry in Beijing, CAS Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China; (L.G.); (X.L.); (Y.Z.); (Y.D.); (J.H.); (Y.Z.); (Y.Z.)
| | - Yang Zhou
- Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, National Centre for Mass Spectrometry in Beijing, CAS Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China; (L.G.); (X.L.); (Y.Z.); (Y.D.); (J.H.); (Y.Z.); (Y.Z.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yang Dou
- Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, National Centre for Mass Spectrometry in Beijing, CAS Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China; (L.G.); (X.L.); (Y.Z.); (Y.D.); (J.H.); (Y.Z.); (Y.Z.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Juanjuan Han
- Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, National Centre for Mass Spectrometry in Beijing, CAS Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China; (L.G.); (X.L.); (Y.Z.); (Y.D.); (J.H.); (Y.Z.); (Y.Z.)
| | - Yao Zhao
- Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, National Centre for Mass Spectrometry in Beijing, CAS Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China; (L.G.); (X.L.); (Y.Z.); (Y.D.); (J.H.); (Y.Z.); (Y.Z.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yanyan Zhang
- Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, National Centre for Mass Spectrometry in Beijing, CAS Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China; (L.G.); (X.L.); (Y.Z.); (Y.D.); (J.H.); (Y.Z.); (Y.Z.)
| | - Qun Luo
- Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, National Centre for Mass Spectrometry in Beijing, CAS Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China; (L.G.); (X.L.); (Y.Z.); (Y.D.); (J.H.); (Y.Z.); (Y.Z.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Fuyi Wang
- College of Traditional Chinese Medicine, Shandong University of Traditional Chinese Medicine, Jinan 250355, China;
- Beijing National Laboratory for Molecular Sciences, CAS Research/Education Center for Excellence in Molecular Sciences, National Centre for Mass Spectrometry in Beijing, CAS Key Laboratory of Analytical Chemistry for Living Biosystems, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China; (L.G.); (X.L.); (Y.Z.); (Y.D.); (J.H.); (Y.Z.); (Y.Z.)
- University of Chinese Academy of Sciences, Beijing 100049, China
| |
Collapse
|
2
|
Forzano I, Mone P, Mottola G, Kansakar U, Salemme L, De Luca A, Tesorio T, Varzideh F, Santulli G. Efficacy of the New Inotropic Agent Istaroxime in Acute Heart Failure. J Clin Med 2022; 11:7503. [PMID: 36556120 PMCID: PMC9786901 DOI: 10.3390/jcm11247503] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2022] [Revised: 12/14/2022] [Accepted: 12/15/2022] [Indexed: 12/24/2022] Open
Abstract
Current therapeutic strategies for acute heart failure (AHF) are based on traditional inotropic agents that are often associated with untoward effects; therefore, finding new effective approaches with a safer profile is dramatically needed. Istaroxime is a novel compound, chemically unrelated to cardiac glycosides, that is currently being studied for the treatment of AHF. Its effects are essentially related to its inotropic and lusitropic positive properties exerted through a dual mechanism of action: activation of the sarcoplasmic reticulum Ca2+ ATPase isoform 2a (SERCA2a) and inhibition of the Na+/K+-ATPase (NKA) activity. The advantages of istaroxime over the available inotropic agents include its lower arrhythmogenic action combined with its capability of increasing systolic blood pressure without augmenting heart rate. However, it has a limited half-life (1 hour) and is associated with adverse effects including pain at the injection site and gastrointestinal issues. Herein, we describe the main mechanism of action of istaroxime and we present a systematic overview of both clinical and preclinical trials testing this drug, underlining the latest insights regarding its adoption in clinical practice for AHF.
Collapse
Affiliation(s)
- Imma Forzano
- Division of Cardiology, Department of Advanced Biomedical Sciences, “Federico II” University, 80131 Naples, Italy
| | - Pasquale Mone
- Division of Cardiology, Department of Medicine, Wilf Family Cardiovascular Research Institute, Einstein Institute for Aging Research, Albert Einstein College of Medicine, New York, NY 10461, USA
| | - Gaetano Mottola
- Casa di Cura “Montevergine”, Mercogliano, 83013 Avellino, Italy
| | - Urna Kansakar
- Division of Cardiology, Department of Advanced Biomedical Sciences, “Federico II” University, 80131 Naples, Italy
| | - Luigi Salemme
- Casa di Cura “Montevergine”, Mercogliano, 83013 Avellino, Italy
| | - Antonio De Luca
- Department of Mental and Physical Health and Preventive Medicine, University of Campania “Vanvitelli”, 81100 Caserta, Italy
| | - Tullio Tesorio
- Casa di Cura “Montevergine”, Mercogliano, 83013 Avellino, Italy
| | - Fahimeh Varzideh
- Division of Cardiology, Department of Advanced Biomedical Sciences, “Federico II” University, 80131 Naples, Italy
| | - Gaetano Santulli
- Division of Cardiology, Department of Advanced Biomedical Sciences, “Federico II” University, 80131 Naples, Italy
- Division of Cardiology, Department of Medicine, Wilf Family Cardiovascular Research Institute, Einstein Institute for Aging Research, Albert Einstein College of Medicine, New York, NY 10461, USA
- Department of Molecular Pharmacology, Einstein-Mount Sinai Diabetes Research Center (ES-DRC), Einstein Institute for Neuroimmunology and Inflammation (INI), Fleischer Institute for Diabetes and Metabolism (FIDAM), Albert Einstein College of Medicine, New York, NY 10461, USA
| |
Collapse
|
3
|
Identification of Na+/K+-ATPase inhibition-independent proarrhythmic ionic mechanisms of cardiac glycosides. Sci Rep 2017; 7:2465. [PMID: 28550304 PMCID: PMC5446409 DOI: 10.1038/s41598-017-02496-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2016] [Accepted: 04/13/2017] [Indexed: 12/17/2022] Open
Abstract
The current study explored the Na+/K+-ATPase (NKA) inhibition-independent proarrhythmic mechanisms of cardiac glycosides (CGs) which are well-known NKA inhibitors. With the cytosolic Ca2+ chelated by EGTA and BAPTA or extracellular Ca2+ replaced by Ba2+, effects of bufadienolides (bufalin (BF) and cinobufagin (CBG)) and cardenolides (ouabain (Oua) and pecilocerin A (PEA)) on the L-type calcium current (ICa,L) were recorded in heterologous expression Cav1.2-CHO cells and human embryonic stem cell-derived cardiomyocytes (hESC-CMs). BF and CBG demonstrated a concentration-dependent (0.1 to 100 µM) ICa,L inhibition (maximal ≥50%) without and with the NKA activity blocked by 10 µM Oua. BF significantly shortened the action potential duration at 1.0 µM and shortened the extracellular field potential duration at 0.01~1.0 µM. On the other hand, BF and CBG at 100 µM demonstrated a strong inhibition (≥40%) of the rapidly activating component of the delayed rectifier K+ current (IKr) in heterologous expression HEK293 cells and prolonged the APD of the heart of day-3 Zebrafish larva with disrupted rhythmic contractions. Moreover, hESC-CMs treated with BF (10 nM) for 24 hours showed moderate yet significant prolongation in APD90. In conclusion, our data indicate that CGs particularly bufadienolides possess cytosolic [Ca2+]i- and NKA inhibition- independent proarrhythmic potential through ICa,L and IKr inhibitions.
Collapse
|
4
|
Wu J, Wang X, Chung YY, Koh CH, Liu Z, Guo H, Yuan Q, Wang C, Su S, Wei H. L-Type Calcium Channel Inhibition Contributes to the Proarrhythmic Effects of Aconitine in Human Cardiomyocytes. PLoS One 2017; 12:e0168435. [PMID: 28056022 PMCID: PMC5215924 DOI: 10.1371/journal.pone.0168435] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 12/01/2016] [Indexed: 01/17/2023] Open
Abstract
Aconitine (ACO) is well-known for causing lethal ventricular tachyarrhythmias. While cardiac Na+ channel opening during repolarization has long been documented in animal cardiac myocytes, the cellular effects and mechanism of ACO in human remain unexplored. This study aimed to assess the proarrhythmic effects of ACO in human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs). ACO concentration-dependently (0.3 ~ 3.0 μM) shortened the action potentials (AP) durations (APD) in ventricular-like hiPSC-CMs by > 40% and induced delayed after-depolarization. Laser-scanning confocal calcium imaging analysis showed that ACO decreased the duration and amplitude of [Ca2+]i transients and increased in the beating frequencies by over 60%. Moreover, ACO was found to markedly reduce the L-type calcium channel (LTCC) currents (ICa,L) in hiPSC-CMs associated with a positive-shift of activation and a negative shift of inactivation. ACO failed to alter the peak and late Na+ currents (INa) in hiPSC-CMs while it drastically increased the late INa in Guinea-pig ventricular myocytes associated with enhanced activation/delayed inactivation of INa at -55 mV~ -85 mV. Further, the effects of ACO on ICa,L, INa and the rapid delayed rectifier potassium current (Ikr) were validated in heterologous expression systems by automated voltage-clamping assays and a moderate suppression of Ikr was observed in addition to concentration-dependent ICa,L inhibition. Lastly, increased beating frequency, decreased Ca2+ wave and shortened field potential duration were recorded from hiPSC-CMs by microelectrode arrays assay. In summary, our data demonstrated that LTCC inhibition could play a main role in the proarrhythmic action of ACO in human cardiomyocytes.
Collapse
Affiliation(s)
- Jianjun Wu
- National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore
| | - Xiangchong Wang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Ying Ying Chung
- National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore
| | - Cai Hong Koh
- National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore
| | - Zhenfeng Liu
- National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore
| | - Huicai Guo
- Department of Toxicology, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Qiang Yuan
- Neuroscience & Behavioral Disorders Program, Duke-NUS Medical School Singapore, Singapore
| | - Chuan Wang
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei, China
| | - Suwen Su
- Department of Pharmacology, Hebei Medical University, Shijiazhuang, Hebei, China
- * E-mail: (HW); (SS)
| | - Heming Wei
- National Heart Research Institute Singapore, National Heart Centre Singapore, Singapore
- Cardiovascular & Metabolic Disorders Program, Duke-NUS Medical School Singapore, Singapore
- * E-mail: (HW); (SS)
| |
Collapse
|
5
|
Sirenko SG, Maltsev VA, Yaniv Y, Bychkov R, Yaeger D, Vinogradova T, Spurgeon HA, Lakatta EG. Electrochemical Na+ and Ca2+ gradients drive coupled-clock regulation of automaticity of isolated rabbit sinoatrial nodal pacemaker cells. Am J Physiol Heart Circ Physiol 2016; 311:H251-67. [PMID: 27208164 DOI: 10.1152/ajpheart.00667.2015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 05/11/2016] [Indexed: 11/22/2022]
Abstract
Coupling of an intracellular Ca(2+) clock to surface membrane ion channels, i.e., a "membrane clock, " via coupling of electrochemical Na(+) and Ca(2+) gradients (ENa and ECa, respectively) has been theorized to regulate sinoatrial nodal cell (SANC) normal automaticity. To test this hypothesis, we measured responses of [Na(+)]i, [Ca(2+)]i, membrane potential, action potential cycle length (APCL), and rhythm in rabbit SANCs to Na(+)/K(+) pump inhibition by the digitalis glycoside, digoxigenin (DG, 10-20 μmol/l). Initial small but significant increases in [Na(+)]i and [Ca(2+)]i and reductions in ENa and ECa in response to DG led to a small reduction in maximum diastolic potential (MDP), significantly enhanced local diastolic Ca(2+) releases (LCRs), and reduced the average APCL. As [Na(+)]i and [Ca(2+)]i continued to increase at longer times following DG exposure, further significant reductions in MDP, ENa, and ECa occurred; LCRs became significantly reduced, and APCL became progressively and significantly prolonged. This was accompanied by increased APCL variability. We also employed a coupled-clock numerical model to simulate changes in ENa and ECa simultaneously with ion currents not measured experimentally. Numerical modeling predicted that, as the ENa and ECa monotonically reduced over time in response to DG, ion currents (ICaL, ICaT, If, IKr, and IbNa) monotonically decreased. In parallel with the biphasic APCL, diastolic INCX manifested biphasic changes; initial INCX increase attributable to enhanced LCR ensemble Ca(2+) signal was followed by INCX reduction as ENCX (ENCX = 3ENa - 2ECa) decreased. Thus SANC automaticity is tightly regulated by ENa, ECa, and ENCX via a complex interplay of numerous key clock components that regulate SANC clock coupling.
Collapse
Affiliation(s)
- Syevda G Sirenko
- Laboratory of Cardiovascular Science, National Institutes of Health, National Institute on Aging, Intramural Research Program, Baltimore, Maryland
| | - Victor A Maltsev
- Laboratory of Cardiovascular Science, National Institutes of Health, National Institute on Aging, Intramural Research Program, Baltimore, Maryland
| | - Yael Yaniv
- Laboratory of Cardiovascular Science, National Institutes of Health, National Institute on Aging, Intramural Research Program, Baltimore, Maryland; Biomedical Engineering Faculty, Technion-IIT, Haifa, Israel
| | - Rostislav Bychkov
- Laboratory of Cardiovascular Science, National Institutes of Health, National Institute on Aging, Intramural Research Program, Baltimore, Maryland; Universidad Central del Caribe, Santa Juanita, Bayamon Puerto Rico
| | - Daniel Yaeger
- Laboratory of Cardiovascular Science, National Institutes of Health, National Institute on Aging, Intramural Research Program, Baltimore, Maryland
| | - Tatiana Vinogradova
- Laboratory of Cardiovascular Science, National Institutes of Health, National Institute on Aging, Intramural Research Program, Baltimore, Maryland
| | - Harold A Spurgeon
- Laboratory of Cardiovascular Science, National Institutes of Health, National Institute on Aging, Intramural Research Program, Baltimore, Maryland
| | - Edward G Lakatta
- Laboratory of Cardiovascular Science, National Institutes of Health, National Institute on Aging, Intramural Research Program, Baltimore, Maryland;
| |
Collapse
|
6
|
Acidosis inhibits spontaneous activity and membrane currents in myocytes isolated from the rabbit atrioventricular node. J Mol Cell Cardiol 2008; 46:75-85. [PMID: 18950636 DOI: 10.1016/j.yjmcc.2008.09.709] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/17/2007] [Revised: 09/23/2008] [Accepted: 09/23/2008] [Indexed: 11/22/2022]
Abstract
Recent evidence from intact hearts suggests that the function of cardiac nodal tissue may be particularly susceptible to acidosis. Little is currently known, however, about the effects of acidosis on the cellular electrophysiology of the atrioventricular node (AVN). This study was conducted, therefore, to determine the effect of acidosis on the spontaneous activity and membrane currents of myocytes isolated from the rabbit AVN, recorded at 35-37 degrees C using whole-cell patch-clamp. Reduction of extracellular pH (pH(e); from 7.4 to 6.8 or 6.3) produced pH-dependent slowing of spontaneous action potential rate and upstroke velocity, and reductions in maximum diastolic potential and action potential amplitude. Ionic current recordings under voltage-clamp indicated that acidosis (pH(e) 6.3) decreased L-type Ca current (I(Ca,L)), without significant changes in voltage-dependent activation or inactivation. Acidosis reduced the E-4031-sensitive, rapid delayed rectifier current (I(Kr)) tail amplitude at -40 mV following command pulses to between -30 and +50 mV, and accelerated tail-current deactivation. In contrast, the time-dependent hyperpolarisation-activated current, I(f), was unaffected by acidosis. Background current insensitive to E-4031 and nifedipine was reduced by acidosis. Measurement of intracellular pH (pH(i)) from undialysed cells using BCECF showed a reduction in mean pH(i) from 7.24 to 6.45 (n=17) when pH(e) was lowered from 7.4 to 6.3. We conclude that I(f) is unlikely to be involved in the response of the AVN to acidosis, whilst inhibition of I(Ca,L) and I(Kr) by acidosis are likely to play a significant role in effects on AVN cellular electrophysiology.
Collapse
|
7
|
Saini HK, Dhalla NS. Sarcolemmal cation channels and exchangers modify the increase in intracellular calcium in cardiomyocytes on inhibiting Na+-K+-ATPase. Am J Physiol Heart Circ Physiol 2007; 293:H169-81. [PMID: 17322410 DOI: 10.1152/ajpheart.00007.2007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Although inhibition of the sarcolemmal (SL) Na+-K+-ATPase is known to cause an increase in the intracellular concentration of Ca2+([Ca2+]i) by stimulating the SL Na+/Ca2+exchanger (NCX), the involvement of other SL sites in inducing this increase in [Ca2+]iis not fully understood. Isolated rat cardiomyocytes were treated with or without different agents that modify Ca2+movements by affecting various SL sites and were then exposed to ouabain. Ouabain was observed to increase the basal levels of both [Ca2+]iand intracellular Na+concentration ([Na+]i) as well as to augment the KCl-induced increases in both [Ca2+]iand [Na+]iin a concentration-dependent manner. The ouabain-induced changes in [Na+]iand [Ca2+]iwere attenuated by treatment with inhibitors of SL Na+/H+exchanger and SL Na+channels. Both the ouabain-induced increase in basal [Ca2+]iand augmentation of the KCl response were markedly decreased when cardiomyocytes were exposed to 0–10 mM Na+. Inhibitors of SL NCX depressed but decreasing extracellular Na+from 105–35 mM augmented the ouabain-induced increase in basal [Ca2+]iand the KCl response. Not only was the increase in [Ca2+]iby ouabain dependent on the extracellular Ca2+concentration, but it was also attenuated by inhibitors of SL L-type Ca2+channels and store-operated Ca2+channels (SOC). Unlike the SL L-type Ca2+-channel blocker, the blockers of SL Na+channel and SL SOC, when used in combination with SL NCX inhibitor, showed additive effects in reducing the ouabain-induced increase in basal [Ca2+]i. These results support the view that in addition to SL NCX, SL L-type Ca2+channels and SL SOC may be involved in raising [Ca2+]ion inhibition of the SL Na+-K+-ATPase by ouabain. Furthermore, both SL Na+/H+exchanger and Na+channels play a critical role in the ouabain-induced Ca2+increase in cardiomyocytes.
Collapse
Affiliation(s)
- Harjot K Saini
- Institute of Cardiovascular Sciences, St. Boniface General Hospital Research Centre, 351 Tache Avenue, Winnipeg, Manitoba, Canada
| | | |
Collapse
|
8
|
Rocchetti M, Besana A, Mostacciuolo G, Ferrari P, Micheletti R, Zaza A. Diverse toxicity associated with cardiac Na+/K+ pump inhibition: evaluation of electrophysiological mechanisms. J Pharmacol Exp Ther 2003; 305:765-71. [PMID: 12606646 DOI: 10.1124/jpet.102.047696] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
(E,Z)-3-((2-Aminoethoxy)imino)androstane-6,17-dione hydrochloride (PST2744) is a novel Na(+)/K(+) pump inhibitor with positive inotropic effects. Compared with digoxin in various experimental models, PST2744 was consistently found to be less arrhythmogenic, thus resulting in a significantly higher therapeutic index. The present work compares the electrophysiological effects of PST2744 and digoxin in guinea pig ventricular myocytes, with the aim to identify a mechanism for their different toxicity. The work showed that 1) the action potential was transiently prolonged and then similarly shortened by both agents; 2) the ratio between Na(+)/K(+) pump inhibition and inotropy was somewhat larger for PST2744 than for digoxin; 3) both agents accelerated inactivation of high-threshold Ca(2+) current (I(CaL)), without affecting its peak amplitude; 4) the transient inward current (I(TI)) induced by a Ca(2+) transient in the presence of complete Na(+)/K(+) pump blockade was inhibited (-43%) by PST2744 but not by digoxin; 5) the conductance of Na(+)/Ca(2+) exchanger current (I(NaCa)), recorded under Na(+)/K(+) pump blockade, was only slightly inhibited by PST2744 (-14%) and unaffected by digoxin; and 6) both agents inhibited delayed rectifier current I(Ks) (<or=-21%); delayed rectifier current I(Kr) was inhibited by PST2744 only, but the effect was marginal (-6%). Thus, 1) the higher therapeutic index of PST2744 may be accounted for by inhibition of I(TI), a current directly involved in digitalis-induced arrhythmias. Indeed, the other differences observed concern quantitatively small effects; and 2) I(TI) suppression by PST2744 may be only partly accounted for by inhibition of the Na(+)/Ca(2+) exchanger.
Collapse
Affiliation(s)
- M Rocchetti
- Dipartimento di Biotecnologie e Bioscienze, Università Milano-Bicocca, Piazza della Scienza 2, Room U3-3013 20126 Milan, Italy
| | | | | | | | | | | |
Collapse
|
9
|
|
10
|
Convery MK, Hancox JC. Na+-Ca2+ exchange current from rabbit isolated atrioventricular nodal and ventricular myocytes compared using action potential and ramp waveforms. ACTA PHYSIOLOGICA SCANDINAVICA 2000; 168:393-401. [PMID: 10712577 DOI: 10.1046/j.1365-201x.2000.00681.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We measured and compared Na-Ca exchanger current (INa-Ca) from rabbit isolated ventricular and atrioventricular (AV) nodal myocytes, using action potential (AP) and ramp voltage commands. Whole cell patch-clamp recordings were made at 35-37 degrees C; INa-Ca was measured as 5 mM nickel (Ni)- sensitive current with major interfering voltage and calcium-activated currents blocked. In ventricular cells a 2-s descending ramp elicited INa-Ca showing outward rectification and a reversal potential (Erev) of -13.1 +/- 1. 2 mV (n = 12; mean +/- SEM). With a ventricular AP as the voltage command, the profile of INa-Ca followed the applied waveform closely. The current-voltage relation during AP repolarization was almost linear and showed an Erev of -38.3 +/- 5.3 mV (n = 6). As INa-Ca depended on the applied voltage waveform, comparisons between the two cell types utilized the same command waveform (a series of AV nodal APs). In ventricular myocytes this elicited INa-Ca that reversed near -38 mV and was inwardly directed during the pacemaker potential. This command was also applied to AV node cells; mean INa-Ca density at all voltages encompassed by the AP (-70 to +30 mV) did not differ significantly from that in ventricular myocytes (P > 0.05, ANOVA). This finding was confirmed using brief (250 ms) voltage ramp protocols (P > 0.1 ANOVA). These data represent the first direct measurements of AV nodal INa-Ca and suggest that the exchanger may be functionally expressed to similar levels in the two cell types. They may also suggest a possible role for INa-Ca during the pacemaker potential in AV node as inward INa-Ca was observed over the pacemaker potential range even with bulk internal Ca buffered to a low level.
Collapse
Affiliation(s)
- M K Convery
- Department of Physiology & Cardiovascular Research Laboratories, School of Medical Sciences, University Walk, Bristol, UK
| | | |
Collapse
|
11
|
Hancox JC, Mitcheson JS. Inhibition of L-type calcium current by propafenone in single myocytes isolated from the rabbit atrioventricular node. Br J Pharmacol 1997; 121:7-14. [PMID: 9146880 PMCID: PMC1564643 DOI: 10.1038/sj.bjp.0701086] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
1. The atrioventricular node (AVN) is an important part of the conduction system in the heart and is a significant site of antiarrhythmic drug action. The class 1 antiarrhythmic propafenone is effective in treating a variety of arrhythmias, including those involving the AVN. In this study, we have investigated the effects of propafenone on ionic currents in single rabbit AVN cells, focusing in particular on those on L-type calcium current (ICa,L). 2. With a standard K-based internal dialysis solution, exposure to 5 microM propafenone reduced significantly the amplitude of ICa,L. In spontaneously active AVN myocytes, action potential upstroke velocity was decreased by propafenone exposure, consistent with the observed change in ICa,L. 3. By use of a Cs-based internal dialysis solution to record ICa,L selectively, voltage clamp test pulses were applied from a holding potential of -40 mV to +10 mV (stimulation frequency 0.33 Hz). Propafenone 5 microM reduced mean ICa,L density at +10 mV from -9.58 +/- 1.05 pA/pF to -4.19 +/- 0.60 pA/pF (P < 0.002). A range of propafenone concentrations were applied which reduced ICa,L in a dose-dependent manner (IC50 1.7 microM). When test pulses were applied to a range of potentials, propafenone reduced ICa,L at each potential without significantly affecting the activation curve for this current. Thus, propafenone reduced ICa,L conductance, without affecting the voltage-dependent activation properties of the current. 4. ICa,L block by propafenone exhibited tonic-, use- and frequency-dependent characteristics. 5. In the presence of propafenone, the voltage-dependence of inactivation of ICa,L was shifted 8 mV in the hyperpolarizing direction. Also, the recovery of ICa,L from inactivation was slowed by propafenone. 6. The ICa,L blocking properties of propafenone may mediate some of the antiarrhythmic properties of this agent, particularly in regions of the heart such as the AVN in which ICa,L contributes significantly to the action potential upstroke.
Collapse
Affiliation(s)
- J C Hancox
- Department of Physiology, School of Medical Sciences, University Walk, Bristol
| | | |
Collapse
|