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Dowrick JM, Taberner AJ, Han JC, Tran K. Methods for assessing cardiac myofilament calcium sensitivity. Front Physiol 2023; 14:1323768. [PMID: 38116581 PMCID: PMC10728676 DOI: 10.3389/fphys.2023.1323768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2023] [Accepted: 11/23/2023] [Indexed: 12/21/2023] Open
Abstract
Myofilament calcium (Ca2+) sensitivity is one of several mechanisms by which force production of cardiac muscle is modulated to meet the ever-changing demands placed on the heart. Compromised Ca2+ sensitivity is associated with pathologies, which makes it a parameter of interest for researchers. Ca2+ Sensitivity is the ratio of the association and dissociation rates between troponin C (TnC) and Ca2+. As it is not currently possible to measure these rates in tissue preparations directly, methods have been developed to infer myofilament sensitivity, typically using some combination of force and Ca2+ measurements. The current gold-standard approach constructs a steady-state force-Ca2+ relation by exposing permeabilised muscle samples to a range of Ca2+ concentrations and uses the half-maximal concentration as a proxy for sensitivity. While a valuable method for steady-state investigations, the permeabilisation process makes the method unsuitable when examining dynamic, i.e., twitch-to-twitch, changes in myofilament sensitivity. The ability of the heart to transiently adapt to changes in load is an important consideration when evaluating the impact of disease states. Alternative methods have been proffered, including force-Ca2+ phase loops, potassium contracture, hybrid experimental-modelling and conformation-based fluorophore approaches. This review provides an overview of the mechanisms underlying myofilament Ca2+ sensitivity, summarises existing methods, and explores, with modelling, whether any of them are suited to investigating dynamic changes in sensitivity. We conclude that a method that equips researchers to investigate the transient change of myofilament Ca2+ sensitivity is still needed. We propose that such a method will involve simultaneous measurements of cytosolic Ca2+ and TnC activation in actively twitching muscle and a biophysical model to interpret these data.
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Affiliation(s)
- Jarrah M. Dowrick
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Andrew J. Taberner
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
- Department of Engineering Science and Biomedical Engineering, University of Auckland, Auckland, New Zealand
| | - June-Chiew Han
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Kenneth Tran
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
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Liu J, Li L, Xie P, Zhao X, Shi D, Zhang Y, Pan C, Li T. Sevoflurane induced neurotoxicity in neonatal mice links to a GSK3β/Drp1-dependent mitochondrial fission and apoptosis. Free Radic Biol Med 2022; 181:72-81. [PMID: 35122996 DOI: 10.1016/j.freeradbiomed.2022.01.031] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2021] [Revised: 01/27/2022] [Accepted: 01/31/2022] [Indexed: 12/01/2022]
Abstract
Mitochondria damage and apoptosis were found associated with sevoflurane induced neurotoxicity in developing brains of rodent and neuro cell lines. The detailed upstream mechanism remains unclear. This study explored whether sevoflurane induces neurotoxicity by activating a GSK3β (glycogen synthase kinase 3β)/Drp1 (dynamin-related protein-1)-dependent mitochondrial fission and apoptosis. Our results showed that sevoflurane exposure promoted mitochondria fission in hippocampus of neonatal mice, resulted in a prolonged escape latency from P32 (32-day-postnatal) to P35, and decreased platform crossing times on P36 as compared to the control treatment. Additionally, sevoflurane upregulated GSK3β stability and activation, promoted phosphorylation of Drp1 at Ser616 along with its translocation to mitochondria and resulted in increasing cytochrome c and cleaved casepase-3 in hippocampus of neonatal mice and in human SK-N-SH cells. Simultaneously, sevoflurane promoted the interaction between Drp1 and GSK3β. Furthermore, GSK3β activated phosphorylation of Drp1 at Ser616, induced mitochondrial fission, loss of mitochondrial membrane potential (MMP) and apoptosis in SK-N-SH cells, which was attenuated by TDZD-8, an inhibitor of GSK3β. In conclusion, sevoflurane induced neurotoxicity links to a GSK3β/Drp1 dependent mitochondrial fission and apoptosis.
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Affiliation(s)
- Jinsheng Liu
- Department of Anesthesiology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Li Li
- Department of Gastroenterology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Ping Xie
- Department of Cell Biology, Municipal Laboratory for Liver Protection and Regulation of Regeneration, Capital Medical University, Beijing, China
| | - Xiaoyan Zhao
- Department of Anesthesiology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Dongjing Shi
- Department of Anesthesiology, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Yan Zhang
- College of Life Science, Peking University, Beijing, China
| | - Chuxiong Pan
- Department of Anesthesiology, Beijing Stomatological Hospital, Capital Medical University, Beijing, China.
| | - Tianzuo Li
- Department of Anesthesiology, Beijing Shijitan Hospital, Capital Medical University, Beijing, China.
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Meng T, Bu W, Ren X, Chen X, Yu J, Eckenhoff RG, Gao WD. Molecular mechanism of anesthetic-induced depression of myocardial contraction. FASEB J 2016; 30:2915-25. [PMID: 27170289 DOI: 10.1096/fj.201600290rr] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 04/26/2016] [Indexed: 01/22/2023]
Abstract
Isoflurane and propofol are known to depress cardiac contraction, but the molecular mechanisms involved are not known. In this study, we determined whether decreasing myofilament Ca(2+) responsiveness underlies anesthesia-induced depression of contraction and uncovered the molecular targets of isoflurane and propofol. Force and intracellular Ca(2+) ([Ca(2+)]i) were measured in rat trabeculae superfused with Krebs-Henseleit solution, with or without propofol or isoflurane. Photoaffinity labeling of myofilament proteins with meta-Azi-propofol (AziPm) and Azi-isoflurane (Azi-iso) and molecular docking were also used. Both propofol and isoflurane dose dependently depressed force from low doses (propofol, 27 ± 6 μM; isoflurane, 1.0 ± 0.1%) to moderate doses (propofol, 87 ± 4 μM; isoflurane, 3.0 ± 0.25%), without significant alteration [Ca(2+)]i During steady-state activations in both intact and skinned preparations, propofol and isoflurane depressed maximum Ca(2+)-activated force and increased the [Ca(2+)]i required for 50% of activation. Myofibrils photolabeled with AziPm and Azi-iso identified myosin, actin, and myosin light chain as targets of the anesthetics. Several adducted residues in those proteins were located in conformationally sensitive regions that underlie contractile function. Thus, propofol and isoflurane decrease force development by directly depressing myofilament Ca(2+) responsiveness and have binding sites in key regions for contraction in both actin and myosin.-Meng, T., Bu, W., Ren, X., Chen, X., Yu, J., Eckenhoff, R. G., Gao, W. D. Molecular mechanism of anesthetic-induced depression of myocardial contraction.
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Affiliation(s)
- Tao Meng
- Department of Anesthesiology, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Weiming Bu
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Xianfeng Ren
- Department of Anesthesiology, China-Japan Friendship Hospital, Beijing, China
| | - Xinzhong Chen
- Department of Cardiac Surgery, Tongji University Medical Center, Wuhan, China; and
| | - Jingui Yu
- Department of Anesthesiology, Qilu Hospital of Shandong University, Jinan, Shandong, China
| | - Roderic G Eckenhoff
- Department of Anesthesiology and Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA;
| | - Wei Dong Gao
- Department of Anesthesiology and Critical Care Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
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Ding W, Li Z, Shen X, Martin J, King SB, Sivakumaran V, Paolocci N, Gao WD. Reversal of isoflurane-induced depression of myocardial contraction by nitroxyl via myofilament sensitization to Ca2+. J Pharmacol Exp Ther 2011; 339:825-31. [PMID: 21865439 DOI: 10.1124/jpet.111.185272] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Isoflurane (ISO) is known to depress cardiac contraction. Here, we hypothesized that decreasing myofilament Ca(2+) responsiveness is central to ISO-induced reduction in cardiac force development. Moreover, we also tested whether the nitroxyl (HNO) donor 1-nitrosocyclohexyl acetate (NCA), acting as a myofilament Ca(2+) sensitizer, restores force in the presence of ISO. Trabeculae from the right ventricles of LBN/F1 rats were superfused with Krebs-Henseleit solution at room temperature, and force and intracellular Ca(2+) ([Ca(2+)](i)) were measured. Steady-state activations were achieved by stimulating the muscles at 10 Hz in the presence of ryanodine. The same muscles were chemically skinned with 1% Triton X-100, and the force-Ca(2+) relation measurements were repeated. ISO depressed force in a dose-dependent manner without significantly altering [Ca(2+)](i). At 1.5%, force was reduced over 50%, whereas [Ca(2+)](i) remained unaffected. At 3%, contraction was decreased by ∼75% with [Ca(2+)](i) reduced by only 15%. During steady-state activation, 1.5% ISO depressed maximal Ca(2+)-activated force (F(max)) and increased the [Ca(2+)](i) required for 50% activation (Ca(50)) without affecting the Hill coefficient. After skinning, the same muscles showed similar decreases in F(max) and increases in Ca(50) in the presence of ISO. NCA restored force in the presence of ISO without affecting [Ca(2+)](i). These results show that 1) ISO depresses cardiac force development by decreasing myofilament Ca(2+) responsiveness, and 2) myofilament Ca(2+) sensitization by NCA can effectively restore force development without further increases in [Ca(2+)](i). The present findings have potential translational value because of the efficiency and efficacy of HNO on ISO-induced myocardial contractile dysfunction.
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Affiliation(s)
- Wengang Ding
- Department of Anesthesiology, 2nd Affiliated Hospital, Harbin Medical University, Heilongjiang, China
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Bouwman RA, Salic K, Padding FG, Eringa EC, van Beek-Harmsen BJ, Matsuda T, Baba A, Musters RJP, Paulus WJ, de Lange JJ, Boer C. Cardioprotection via activation of protein kinase C-delta depends on modulation of the reverse mode of the Na+/Ca2+ exchanger. Circulation 2006; 114:I226-32. [PMID: 16820577 DOI: 10.1161/circulationaha.105.000570] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Pretreatment with the volatile anesthetic sevoflurane protects cardiomyocytes against subsequent ischemic episodes caused by a protein kinase C (PKC)-delta mediated preconditioning effect. Sevoflurane directly modulates cardiac Ca2+ handling, and because Ca2+ also serves as a mediator in other cardioprotective signaling pathways, possible involvement of the Na+/Ca2+ exchanger (NCX) in relation with PKC-delta in sevoflurane-induced cardioprotection was investigated. METHODS AND RESULTS Isolated right ventricular rat trabeculae were subjected to simulated ischemia and reperfusion (SI/R), consisting of superfusion with hypoxic glucose-free buffer for 40 minutes after rigor development, followed by reperfusion with normoxic glucose containing buffer. Preconditioning with sevoflurane before SI/R improved isometric force development during contractile recovery at 60 minutes after the end of hypoxic superfusion (83+/-7% [sevo] versus 57+/-2% [SI/R];n=8; P<0.01). Inhibition of the reverse mode of the NCX by KB-R7943 (10 micromol/L) or SEA0400 (1 micromol/L) during preconditioning attenuated the protective effect of sevoflurane. KB-R7943 and SEA0400 did not have intrinsic effects on the contractile recovery. Furthermore, inhibition of the NCX in trabeculae exposed to sevoflurane reduced sevoflurane-induced PKC-delta translocation toward the sarcolemma, as demonstrated by digital imaging fluorescent microscopy. The degree of PKC-delta phosphorylation at serine643 as determined by western blot analysis was not affected by sevoflurane. CONCLUSIONS Sevoflurane-induced cardioprotection depends on the NCX preceding PKC-delta translocation presumably via increased NCX-mediated Ca2+ influx. This may suggest that increased myocardial Ca2+ load triggers the cardioprotective signaling cascade elicited by volatile anesthetic agents similar to other modes of preconditioning.
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Affiliation(s)
- R Arthur Bouwman
- Department of Anesthesiology, VU University Medical Center, de Boelelaan 1118, PO Box 7057, 1007 MB Amsterdam, Netherlands.
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Duke AM, Hopkins PM, Halsall PJ, Steele DS. Mg2+ dependence of Ca2+ release from the sarcoplasmic reticulum induced by sevoflurane or halothane in skeletal muscle from humans susceptible to malignant hyperthermia. Br J Anaesth 2006; 97:320-8. [PMID: 16849381 DOI: 10.1093/bja/ael179] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND In normal resting muscle, cytosolic Mg(2+) exerts a potent inhibitory influence on the sarcoplasmic reticulum (SR) Ca(2+) release channel (ryanodine receptor, RyR1). Impaired Mg(2+)-regulation of RyR1 has been proposed as a causal factor in malignant hyperthermia (MH). The aim of this study was to compare the effects of cytosolic Mg(2+) on SR Ca(2+) release induced by halothane or sevoflurane in normal (MHN) and MH susceptible (MHS) human skeletal muscle fibres. METHODS Samples of vastus medialis muscle were obtained from patients under investigation for MH susceptibility. Single fibres were mechanically skinned and perfused with solutions mimicking the intracellular milieu. Changes in [Ca(2+)](i) were detected using fura-2 fluorescence after application of equimolar halothane or sevoflurane. RESULTS In MHN fibres, concentrations of sevoflurane or halothane as high as 10 mM typically failed to induce SR Ca(2+) release at physiological free [Mg(2+)] (1 mM). However, when [Mg(2+)] was decreased to 0.4 mM, SR Ca(2+) release occurred in 51% (16/33) and 6% (2/33) of MHN fibres after the addition of 1 mM halothane or 1 mM sevoflurane, respectively. Further decreases in [Mg(2+)] increased the proportion of responsive fibres. In the presence of 0.1 mM [Mg(2+)], Ca(2+) release occurred in all fibres (33/33) after the introduction of 1 mM halothane or 1 mM sevoflurane. In MHS fibres, 1 mM halothane or 1 mM sevoflurane-induced Ca(2+) release in 54% (7/13) or 15% (2/13) of fibres, respectively, at 1 mM Mg(2+). A decrease in [Mg(2+)] to 0.2 mM Mg(2+) was sufficient to render 100% of MHS fibres (13/13) responsive to 1 mM halothane or 1 mM sevoflurane. CONCLUSIONS In both MHS and MHN fibres (i) halothane is a more potent activator of SR Ca(2+) release than sevoflurane and (ii) as with halothane, the efficacy of sevoflurane-induced SR Ca(2+) release exhibits a marked dependence on cytosolic [Mg(2+)]. The marked potentiation of SR Ca(2+) release after a moderate reduction in cytosolic [Mg(2+)] suggests that conditions which cause hypomagnesaemia will increase the probability and possibly severity of an MH event. Conversely, maintenance of a normal or slightly increased cytosolic [Mg(2+)] may reduce the probability of MH.
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Affiliation(s)
- A M Duke
- Institute of Membrane and Systems Biology, University of Leeds Woodhouse Lane, Leeds LS2 9JT, UK
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Bru-Mercier G, Hopkins PM, Harrison SM. Halothane and sevoflurane inhibit Na/Ca exchange current in rat ventricular myocytes. Br J Anaesth 2005; 95:305-9. [PMID: 15994848 DOI: 10.1093/bja/aei185] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND The electrogenic Na+/Ca2+ exchanger (NCX) represents the main extrusion pathway for Ca2+ in ventricular muscle and therefore plays an important role in the regulation of cytosolic Ca2+ and contraction. Halothane and sevoflurane modulate cytosolic Ca2+ regulation and at steady state are negatively inotropic, however, the involvement of anaesthetic-induced changes in NCX activity in these effects requires further study. METHODS Ventricular myocytes were isolated using a standard collagenase/protease dispersion technique and superfused with a physiological salt solution at 30 degrees C. Whole-cell patch-clamp technique was used to control membrane voltage. I(NCX) (identified as Ni2+ sensitive current) was recorded using a ramp clamp protocol under conditions to inhibit contaminating currents. RESULTS With 0.6 mM sevoflurane, outward I(NCX) at positive voltages (> or = 0 mV) and inward I(NCX) at voltages negative to -60 mV was significantly reduced (P<0.05, n=13; I(NCX) reduced by 48% at +50 and 65% of control at -120 mV). Halothane (0.6 mM) inhibited outward I(NCX) at voltages positive to -10 mV and inward I(NCX) at voltages negative to -80 mV (P<0.05, n=10; I(NCX) reduced by 64% at +50 and 65% of control at -120 mV). Anaesthetic-induced inhibition of both inward and outward current was not voltage-dependent. CONCLUSIONS Inhibition of Ca2+ efflux via NCX (i.e. inward I(NCX)) during an exposure to halothane or sevoflurane would be expected to limit the negative inotropic effects of these agents and help maintain SR Ca2+ content.
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Affiliation(s)
- G Bru-Mercier
- School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK
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