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Marcucci L, Nogara L, Canato M, Germinario E, Raffaello A, Carraro M, Bernardi P, Pietrangelo L, Boncompagni S, Protasi F, Paolocci N, Reggiani C. Mitochondria can substitute for parvalbumin to lower cytosolic calcium levels in the murine fast skeletal muscle. Acta Physiol (Oxf) 2024; 240:e14208. [PMID: 39077881 DOI: 10.1111/apha.14208] [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: 10/23/2023] [Revised: 07/09/2024] [Accepted: 07/15/2024] [Indexed: 07/31/2024]
Abstract
AIM Parvalbumin (PV) is a primary calcium buffer in mouse fast skeletal muscle fibers. Previous work showed that PV ablation has a limited impact on cytosolic Ca2+ ([Ca2+]cyto) transients and contractile response, while it enhances mitochondrial density and mitochondrial matrix-free calcium concentration ([Ca2+]mito). Here, we aimed to quantitatively test the hypothesis that mitochondria act to compensate for PV deficiency. METHODS We determined the free Ca2+ redistribution during a 2 s 60 Hz tetanic stimulation in the sarcoplasmic reticulum, cytosol, and mitochondria. Via a reaction-diffusion Ca2+ model, we quantitatively evaluated mitochondrial uptake and storage capacity requirements to compensate for PV lack and analyzed possible extracellular export. RESULTS [Ca2+]mito during tetanic stimulation is greater in knock-out (KO) (1362 ± 392 nM) than in wild-type (WT) (855 ± 392 nM), p < 0.05. Under the assumption of a non-linear intramitochondrial buffering, the model predicts an accumulation of 725 μmoles/L fiber (buffering ratio 1:11 000) in KO, much higher than in WT (137 μmoles/L fiber, ratio 1:4500). The required transport rate via mitochondrial calcium uniporter (MCU) reaches 3 mM/s, compatible with available literature. TEM images of calcium entry units and Mn2+ quenching showed a greater capacity of store-operated calcium entry in KO compared to WT. However, levels of [Ca2+]cyto during tetanic stimulation were not modulated to variations of extracellular calcium. CONCLUSIONS The model-based analysis of experimentally determined calcium distribution during tetanic stimulation showed that mitochondria can act as a buffer to compensate for the lack of PV. This result contributes to a better understanding of mitochondria's role in modulating [Ca2+]cyto in skeletal muscle fibers.
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Affiliation(s)
- Lorenzo Marcucci
- Department of Biomedical Sciences, University of Padova, Padova, Italy
- Center for Biosystems Dynamics Research, RIKEN, Suita, Japan
| | - Leonardo Nogara
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Marta Canato
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Elena Germinario
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Anna Raffaello
- Department of Biomedical Sciences, University of Padova, Padova, Italy
- Myology Center, University of Padova, Padova, Italy
| | - Michela Carraro
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Paolo Bernardi
- Department of Biomedical Sciences, University of Padova, Padova, Italy
| | - Laura Pietrangelo
- CAST, Center for Advanced Studies and Technology, University G. d'Annunzio of Chieti-Pescara, Chieti, Italy
- DMSI, Department of Medicine and Aging Sciences, University G. d'Annunzio of Chieti-Pescara, Chieti, Italy
| | - Simona Boncompagni
- CAST, Center for Advanced Studies and Technology, University G. d'Annunzio of Chieti-Pescara, Chieti, Italy
- DNICS, Department of Neuroscience and Clinical Sciences, University G. d'Annunzio of Chieti-Pescara, Chieti, Italy
| | - Feliciano Protasi
- CAST, Center for Advanced Studies and Technology, University G. d'Annunzio of Chieti-Pescara, Chieti, Italy
- DMSI, Department of Medicine and Aging Sciences, University G. d'Annunzio of Chieti-Pescara, Chieti, Italy
| | - Nazareno Paolocci
- Department of Biomedical Sciences, University of Padova, Padova, Italy
- Division of Cardiology, The Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Carlo Reggiani
- Department of Biomedical Sciences, University of Padova, Padova, Italy
- Science and Research Center Koper, Institute for Kinesiology Research, Koper, Slovenia
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Sołtys K, Tarczewska A, Bystranowska D. Modulation of biomolecular phase behavior by metal ions. BIOCHIMICA ET BIOPHYSICA ACTA. MOLECULAR CELL RESEARCH 2023; 1870:119567. [PMID: 37582439 DOI: 10.1016/j.bbamcr.2023.119567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 08/04/2023] [Accepted: 08/08/2023] [Indexed: 08/17/2023]
Abstract
Liquid-liquid phase separation (LLPS) appears to be a newly appreciated aspect of the cellular organization of biomolecules that leads to the formation of membraneless organelles (MLOs). MLOs generate distinct microenvironments where particular biomolecules are highly concentrated compared to those in the surrounding environment. Their thermodynamically driven formation is reversible, and their liquid nature allows them to fuse with each other. Dysfunctional biomolecular condensation is associated with human diseases. Pathological states of MLOs may originate from the mutation of proteins or may be induced by other factors. In most aberrant MLOs, transient interactions are replaced by stronger and more rigid interactions, preventing their dissolution, and causing their uncontrolled growth and dysfunction. For these reasons, there is great interest in identifying factors that modulate LLPS. In this review, we discuss an enigmatic and mostly unexplored aspect of this process, namely, the regulatory effects of metal ions on the phase behavior of biomolecules.
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Affiliation(s)
- Katarzyna Sołtys
- Department of Biochemistry, Molecular Biology and Biotechnology, Faculty of Chemistry, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland.
| | - Aneta Tarczewska
- Department of Biochemistry, Molecular Biology and Biotechnology, Faculty of Chemistry, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - Dominika Bystranowska
- Department of Biochemistry, Molecular Biology and Biotechnology, Faculty of Chemistry, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
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Reggiani C, Marcucci L. A controversial issue: Can mitochondria modulate cytosolic calcium and contraction of skeletal muscle fibers? J Gen Physiol 2022; 154:213356. [PMID: 35849108 PMCID: PMC9297197 DOI: 10.1085/jgp.202213167] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Mitochondria are characterized by a high capacity to accumulate calcium thanks to the electrochemical gradient created by the extrusion of protons in the respiratory chain. Thereby calcium can enter crossing the inner mitochondrial membrane via MCU complex, a high-capacity, low-affinity transport mechanism. Calcium uptake serves numerous purposes, among them the regulation of three dehydrogenases of the citric cycle, apoptosis via permeability transition, and, in some cell types, modulation of cytosolic calcium transients. This Review is focused on mitochondrial calcium uptake in skeletal muscle fibers and aims to reanalyze its functional impact. In particular, we ask whether mitochondrial calcium uptake is relevant for the control of cytosolic calcium transients and therefore of contractile performance. Recent data suggest that this may be the case, at least in particular conditions, as modified expression of MCU complex subunits or of proteins involved in mitochondrial dynamics and ablation of the main cytosolic calcium buffer, parvalbumin.
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Affiliation(s)
- Carlo Reggiani
- Department of Biomedical Sciences, University of Padova, Padova, Italy,Science and Research Center Koper, Institute for Kinesiology Research, Koper, Slovenia,Correspondence to Carlo Reggiani:
| | - Lorenzo Marcucci
- Department of Biomedical Sciences, University of Padova, Padova, Italy,Center for Biosystems Dynamics Research, RIKEN, Suita, Japan
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Qiu H, Shen R, Chen L, Pandey S, Sun J, Deng H. Low Serum Magnesium Levels Are Associated With Hemorrhagic Transformation After Mechanical Thrombectomy in Patients With Acute Ischemic Stroke. Front Neurol 2022; 13:831232. [PMID: 35401415 PMCID: PMC8984269 DOI: 10.3389/fneur.2022.831232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 01/31/2022] [Indexed: 11/13/2022] Open
Abstract
Objective In patients with acute ischemic stroke (AIS), hemorrhagic transformation (HT) is a major complication after mechanical thrombectomy (MT). This study aimed to investigate the relationship between serum magnesium levels and HT after MT. Methods We collected 199 cases of consecutive AIS that received MT due to acute anterior circulation occlusions in our institution between January 2017 and January 2020. Baseline serum magnesium was obtained from all patients on admission before MT. The patients were divided into two groups based on the occurrence of HT. Univariate and multivariate analyses were performed to investigate whether magnesium was an independent predictor of HT. The receiver operating characteristic (ROC) curve and area under the curve (AUC) were determined. Results Of the 199 enrolled patients, 40 (20.1%) presented with HT, and 12 (6%) developed symptomatic intracranial hemorrhage (sICH). Patients with HT had lower serum magnesium levels compared to those without HT (0.76 [0.69–0.80] vs. 0.84 [0.80–0.90], p < 0.001). The multivariate logistic analysis showed that the serum magnesium level (odds ratio, [OR]: 0.000, 95% confidence interval [CI]: 0.000–0.001, p < 0.001) was significantly associated with the occurrence of HT. The ROC curve analysis revealed that the serum magnesium level could predict HT with an AUC of.820 (95% CI: 0.750–0.891 p < 0.001). Serum magnesium ≤ 0.80 mmol/L could predict HT with a sensitivity of 79.2% and a specificity of 70.0%. Of interest, the serum magnesium level was not associated with HT when the baseline of serum magnesium was higher than the cut-off value (0.80 mmol/L) in the subgroup analysis. Conclusions Lower baseline serum magnesium levels (<0.80 mmol/L) on admission are associated with increased risk of HT in AIS patients receiving MT.
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Affiliation(s)
- Huijia Qiu
- Department of Neurosurgery, Shanghai Tenth People's Hospital, Tongji University, Shanghai, China
| | - Rui Shen
- Department of Neurosurgery, Shanghai Tenth People's Hospital, Tongji University, Shanghai, China
| | - Liuwei Chen
- Department of Neurosurgery, Shanghai Tenth People's Hospital, Tongji University, Shanghai, China
| | - Sajan Pandey
- Department of Neurosurgery, Shanghai Tenth People's Hospital, Tongji University, Shanghai, China
| | - Jiping Sun
- Department of Neurosurgery, Shanghai Tenth People's Hospital, Tongji University, Shanghai, China
| | - Haoyu Deng
- Department of Medicine, Faculty of Medicine, University of British Columbia, Vancouver, BC, Canada
- Centre for Heart and Lung Innovation, St.Paul's Hospital, University of British Columbia, Vancouver, BC, Canada
- Department of Vascular Surgery, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, China
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Rapid Treatment with Intramuscular Magnesium Sulfate During Cardiopulmonary Resuscitation Does Not Provide Neuroprotection Following Cardiac Arrest. Mol Neurobiol 2022; 59:1872-1881. [PMID: 35028899 DOI: 10.1007/s12035-021-02645-x] [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: 08/27/2021] [Accepted: 11/11/2021] [Indexed: 10/19/2022]
Abstract
Brain injury is the most common cause of death for patients resuscitated from cardiac arrest. Magnesium is an attractive neuroprotective compound which protects neurons from ischemic injury by reducing neuronal calcium overload via NMDA receptor modulation and preventing calcium-induced mitochondrial permeability transition. Intramuscular (IM) delivery of MgSO4 during CPR has the potential to target these mechanisms within an early therapeutic window. We hypothesize that IM MgSO4 administrated during CPR could achieve therapeutic serum magnesium levels within 15 min after ROSC and improve neurologic outcomes in a rat model of asphyxial cardiac arrest. Male Long Evans rats were subjected to 8-min asphyxial cardiac arrest and block randomized to receive placebo, 107 mg/kg, 215 mg/kg, or 430 mg/kg MgSO4 IM at the onset of CPR. Serum magnesium concentrations increased rapidly with IM delivery during CPR, achieving twofold to fourfold increase by 15 min after ROSC in all magnesium dose groups. Rats subjected to cardiac arrest or sham surgery were block randomized to treatment groups for assessment of neurological outcomes. We found that IM MgSO4 during CPR had no effect on ROSC rate (p > 0.05). IM MgSO4 treatment had no statistically significant effect on 10-day survival with good neurologic function or hippocampal CA1 pyramidal neuron survival compared to placebo treatment. In conclusion, a single dose IM MgSO4 during CPR achieves up to fourfold baseline serum magnesium levels within 15 min after ROSC; however, this treatment strategy did not improve survival, recovery of neurologic function, or neuron survival. Future studies with repeated dosing or in combination with hypothermic targeted temperature management may be indicated.
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Neuroprotective effect of magnesium supplementation on cerebral ischemic diseases. Life Sci 2021; 272:119257. [PMID: 33631176 DOI: 10.1016/j.lfs.2021.119257] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 01/31/2021] [Accepted: 02/19/2021] [Indexed: 02/07/2023]
Abstract
Ischemic encephalopathy is associated with a high mortality and rate of disability. The most common type of ischemic encephalopathy, ischemic stroke, is the second leading cause of death in the world. At present, the main treatment for ischemic stroke is to reopen blocked blood vessels. However, despite revascularization, many patients are not able to achieve good functional results. At the same time, the strict time window (<4.5 h) of thrombolytic therapy limits clinical application. Therefore, it is important to explore effective neuroprotective drugs for the treatment of ischemic stroke. Magnesium is a natural calcium antagonist, which exerts neuroprotective effects through various mechanisms. However, while most basic studies have shown that magnesium supplementation can help treat cerebral ischemia, intravenous magnesium supplementation in large clinical trials has failed to improve prognosis of ischemic patients. Therefore, we review the basic and clinical studies of magnesium supplementation for cerebral ischemia. According to the route of administration, treatment can be divided into intraperitoneal magnesium supplementation, intravenous magnesium supplementation, arterial magnesium supplementation and intracranial magnesium supplementation. We also summarized the potential influencing factors of magnesium ion intervention in cerebral ischemia injury. Finally, in combination with influencing factors derived from basic research, this article proposes three future research directions, including magnesium supplementation into the circulatory system combined with magnesium supplementation in the lateral ventricle, magnesium supplementation in the lateral ventricle combined with hypothermia therapy, and lateral ventricle magnesium supplementation combined with intracarotid magnesium supplementation combined with selective hypothermia.
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Tan G, Yuan R, Wei C, Xu M, Liu M. Serum magnesium but not calcium was associated with hemorrhagic transformation in stroke overall and stroke subtypes: a case-control study in China. Neurol Sci 2018; 39:1437-1443. [PMID: 29804167 DOI: 10.1007/s10072-018-3445-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Accepted: 05/09/2018] [Indexed: 02/05/2023]
Abstract
Association between serum calcium and magnesium versus hemorrhagic transformation (HT) remains to be identified. A total of 1212 non-thrombolysis patients with serum calcium and magnesium collected within 24 h from stroke onset were enrolled. Backward stepwise multivariate logistic regression analysis was conducted to investigate association between calcium and magnesium versus HT. Calcium and magnesium were entered into logistic regression analysis in two models, separately: model 1, as continuous variable (per 1-mmol/L increase), and model 2, as four-categorized variable (being collapsed into quartiles). HT occurred in 140 patients (11.6%). Serum calcium was slightly lower in patients with HT than in patient without HT (P = 0.273). But serum magnesium was significantly lower in patients with HT than in patients without HT (P = 0.007). In logistic regression analysis, calcium displayed no association with HT. Magnesium, as either continuous or four-categorized variable, was independently and inversely associated with HT in stroke overall and stroke of large-artery atherosclerosis (LAA). The results demonstrated that serum calcium had no association with HT in patients without thrombolysis after acute ischemic stroke. Serum magnesium in low level was independently associated with increasing HT in stroke overall and particularly in stroke of LAA.
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Affiliation(s)
- Ge Tan
- Stroke Clinical Research Unit, Department of Neurology, West China Hospital, Sichuan University, No. 37, Guo Xue Xiang, Chengdu, 610041, Sichuan Province, China
| | - Ruozhen Yuan
- Stroke Clinical Research Unit, Department of Neurology, West China Hospital, Sichuan University, No. 37, Guo Xue Xiang, Chengdu, 610041, Sichuan Province, China
| | - ChenChen Wei
- Stroke Clinical Research Unit, Department of Neurology, West China Hospital, Sichuan University, No. 37, Guo Xue Xiang, Chengdu, 610041, Sichuan Province, China
| | - Mangmang Xu
- Stroke Clinical Research Unit, Department of Neurology, West China Hospital, Sichuan University, No. 37, Guo Xue Xiang, Chengdu, 610041, Sichuan Province, China
| | - Ming Liu
- Stroke Clinical Research Unit, Department of Neurology, West China Hospital, Sichuan University, No. 37, Guo Xue Xiang, Chengdu, 610041, Sichuan Province, China.
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The Involvement of Mg 2+ in Regulation of Cellular and Mitochondrial Functions. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2017; 2017:6797460. [PMID: 28757913 PMCID: PMC5516748 DOI: 10.1155/2017/6797460] [Citation(s) in RCA: 91] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/24/2017] [Accepted: 05/31/2017] [Indexed: 12/11/2022]
Abstract
Mg2+ is an essential mineral with pleotropic impacts on cellular physiology and functions. It acts as a cofactor of several important enzymes, as a regulator of ion channels such as voltage-dependent Ca2+ channels and K+ channels and on Ca2+-binding proteins. In general, Mg2+ is considered as the main intracellular antagonist of Ca2+, which is an essential secondary messenger initiating or regulating a great number of cellular functions. This review examines the effects of Mg2+ on mitochondrial functions with a particular focus on energy metabolism, mitochondrial Ca2+ handling, and apoptosis.
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From Stores to Sinks: Structural Mechanisms of Cytosolic Calcium Regulation. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 981:215-251. [PMID: 29594864 DOI: 10.1007/978-3-319-55858-5_10] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/08/2022]
Abstract
All eukaryotic cells have adapted the use of the calcium ion (Ca2+) as a universal signaling element through the evolution of a toolkit of Ca2+ sensor, buffer and effector proteins. Among these toolkit components, integral and peripheral proteins decorate biomembranes and coordinate the movement of Ca2+ between compartments, sense these concentration changes and elicit physiological signals. These changes in compartmentalized Ca2+ levels are not mutually exclusive as signals propagate between compartments. For example, agonist induced surface receptor stimulation can lead to transient increases in cytosolic Ca2+ sourced from endoplasmic reticulum (ER) stores; the decrease in ER luminal Ca2+ can subsequently signal the opening surface channels which permit the movement of Ca2+ from the extracellular space to the cytosol. Remarkably, the minuscule compartments of mitochondria can function as significant cytosolic Ca2+ sinks by taking up Ca2+ in a coordinated manner. In non-excitable cells, inositol 1,4,5 trisphosphate receptors (IP3Rs) on the ER respond to surface receptor stimulation; stromal interaction molecules (STIMs) sense the ER luminal Ca2+ depletion and activate surface Orai1 channels; surface Orai1 channels selectively permit the movement of Ca2+ from the extracellular space to the cytosol; uptake of Ca2+ into the matrix through the mitochondrial Ca2+ uniporter (MCU) further shapes the cytosolic Ca2+ levels. Recent structural elucidations of these key Ca2+ toolkit components have improved our understanding of how they function to orchestrate precise cytosolic Ca2+ levels for specific physiological responses. This chapter reviews the atomic-resolution structures of IP3R, STIM1, Orai1 and MCU elucidated by X-ray crystallography, electron microscopy and NMR and discusses the mechanisms underlying their biological functions in their respective compartments within the cell.
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Lee SK, Shanmughapriya S, Mok MC, Dong Z, Tomar D, Carvalho E, Rajan S, Junop MS, Madesh M, Stathopulos PB. Structural Insights into Mitochondrial Calcium Uniporter Regulation by Divalent Cations. Cell Chem Biol 2016; 23:1157-1169. [PMID: 27569754 PMCID: PMC5035232 DOI: 10.1016/j.chembiol.2016.07.012] [Citation(s) in RCA: 66] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 07/04/2016] [Accepted: 07/13/2016] [Indexed: 12/22/2022]
Abstract
Calcium (Ca(2+)) flux into the matrix is tightly controlled by the mitochondrial Ca(2+) uniporter (MCU) due to vital roles in cell death and bioenergetics. However, the precise atomic mechanisms of MCU regulation remain unclear. Here, we solved the crystal structure of the N-terminal matrix domain of human MCU, revealing a β-grasp-like fold with a cluster of negatively charged residues that interacts with divalent cations. Binding of Ca(2+) or Mg(2+) destabilizes and shifts the self-association equilibrium of the domain toward monomer. Mutational disruption of the acidic face weakens oligomerization of the isolated matrix domain and full-length human protein similar to cation binding and markedly decreases MCU activity. Moreover, mitochondrial Mg(2+) loading or blockade of mitochondrial Ca(2+) extrusion suppresses MCU Ca(2+)-uptake rates. Collectively, our data reveal that the β-grasp-like matrix region harbors an MCU-regulating acidic patch that inhibits human MCU activity in response to Mg(2+) and Ca(2+) binding.
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Affiliation(s)
- Samuel K. Lee
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada, N6A 5C1
| | - Santhanam Shanmughapriya
- Department of Molecular Genetics and Molecular Biochemistry, Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA, 19140
| | - Mac C.Y. Mok
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, Canada, L8S 4K1
| | - Zhiwei Dong
- Department of Molecular Genetics and Molecular Biochemistry, Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA, 19140
| | - Dhanendra Tomar
- Department of Molecular Genetics and Molecular Biochemistry, Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA, 19140
| | - Edmund Carvalho
- Department of Molecular Genetics and Molecular Biochemistry, Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA, 19140
| | - Sudarsan Rajan
- Department of Molecular Genetics and Molecular Biochemistry, Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA, 19140
| | - Murray S. Junop
- Department of Biochemistry, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada, N6A 5C1
| | - Muniswamy Madesh
- Department of Molecular Genetics and Molecular Biochemistry, Center for Translational Medicine, Lewis Katz School of Medicine, Temple University, Philadelphia, PA, USA, 19140
| | - Peter B. Stathopulos
- Department of Physiology and Pharmacology, Schulich School of Medicine and Dentistry, Western University, London, ON, Canada, N6A 5C1
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Huang Z, Filipovic Z, Mp N, Ung C, Troy EL, Colburn RW, Iaci JF, Hackett C, Button DC, Caggiano AO, Parry TJ. AC105 Increases Extracellular Magnesium Delivery and Reduces Excitotoxic Glutamate Exposure within Injured Spinal Cords in Rats. J Neurotrauma 2016; 34:685-694. [PMID: 27503053 DOI: 10.1089/neu.2016.4607] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Magnesium (Mg2+) homeostasis is impaired following spinal cord injury (SCI) and the loss of extracellular Mg2+ contributes to secondary injury by various mechanisms, including glutamate neurotoxicity. The neuroprotective effects of high dose Mg2+ supplementation have been reported in many animal models. Recent studies found that lower Mg2+ doses also improved neurologic outcomes when Mg2+ was formulated with polyethylene glycol (PEG), suggesting that a PEG/ Mg2+ formulation might increase Mg2+ delivery to the injured spinal cord, compared with that of MgSO4 alone. Here, we assessed spinal extracellular Mg2+ and glutamate levels following SCI in rats using microdialysis. Basal levels of extracellular Mg2+ (∼0.5 mM) were significantly reduced to 0.15 mM in the core and 0.12 mM in the rostral peri-lesion area after SCI. A single intravenous infusion of saline or of MgSO4 at 192 μmoL/kg did not significantly change extracellular Mg2+ concentrations. However, a single infusion of AC105 (a MgCl2 in PEG) at an equimolar Mg2+ dose significantly increased the Mg2+ concentration to 0.3 mM (core area) and 0.25 mM (rostral peri-lesion area). Moreover, multiple AC105 treatments completely restored the depleted extracellular Mg2+ concentrations after SCI to levels in the uninjured spinal cord. Repeated MgSO4 infusions slightly increased the Mg2+ concentrations while saline infusion had no effect. In addition, AC105 treatment significantly reduced extracellular glutamate levels in the lesion center after SCI. These results indicate that intravenous infusion of PEG-formulated Mg2+ normalized the Mg2+ homeostasis following SCI and reduced potentially neurotoxic glutamate levels, consistent with a neuroprotective mechanism of blocking excitotoxicity.
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Affiliation(s)
| | | | | | - Chia Ung
- Acorda Therapeutics, Inc. , Ardsley, New York
| | | | | | | | | | | | | | - Tom J Parry
- Acorda Therapeutics, Inc. , Ardsley, New York
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Seidlmayer LK, Kuhn J, Berbner A, Arias-Loza PA, Williams T, Kaspar M, Czolbe M, Kwong JQ, Molkentin JD, Heinze KG, Dedkova EN, Ritter O. Inositol 1,4,5-trisphosphate-mediated sarcoplasmic reticulum-mitochondrial crosstalk influences adenosine triphosphate production via mitochondrial Ca2+ uptake through the mitochondrial ryanodine receptor in cardiac myocytes. Cardiovasc Res 2016; 112:491-501. [PMID: 27496868 DOI: 10.1093/cvr/cvw185] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 06/21/2016] [Indexed: 12/22/2022] Open
Abstract
AIMS Elevated levels of inositol 1,4,5-trisphosphate (IP3) in adult cardiac myocytes are typically associated with the development of cardiac hypertrophy, arrhythmias, and heart failure. IP3 enhances intracellular Ca(2+ )release via IP3 receptors (IP3Rs) located at the sarcoplasmic reticulum (SR). We aimed to determine whether IP3-induced Ca(2+ )release affects mitochondrial function and determine the underlying mechanisms. METHODS AND RESULTS We compared the effects of IP3Rs- and ryanodine receptors (RyRs)-mediated cytosolic Ca(2+ )elevation achieved by endothelin-1 (ET-1) and isoproterenol (ISO) stimulation, respectively, on mitochondrial Ca(2+ )uptake and adenosine triphosphate (ATP) generation. Both ET-1 and isoproterenol induced an increase in mitochondrial Ca(2+ )(Ca(2 +) m) but only ET-1 led to an increase in ATP concentration. ET-1-induced effects were prevented by cell treatment with the IP3 antagonist 2-aminoethoxydiphenyl borate and absent in myocytes from transgenic mice expressing an IP3 chelating protein (IP3 sponge). Furthermore, ET-1-induced mitochondrial Ca(2+) uptake was insensitive to the mitochondrial Ca(2+ )uniporter inhibitor Ru360, however was attenuated by RyRs type 1 inhibitor dantrolene. Using real-time polymerase chain reaction, we detected the presence of all three isoforms of IP3Rs and RyRs in murine ventricular myocytes with a dominant presence of type 2 isoform for both receptors. CONCLUSIONS Stimulation of IP3Rs with ET-1 induces Ca(2+ )release from the SR which is tunnelled to mitochondria via mitochondrial RyR leading to stimulation of mitochondrial ATP production.
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Affiliation(s)
- Lea K Seidlmayer
- Department of Internal Medicine, Cardiology, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080 Würzburg, Germany Comprehensive Heart Failure Center, University of Würzburg, Straubmühlweg 2a, 97078 Würzburg, Germany
| | - Johannes Kuhn
- Department of Internal Medicine, Cardiology, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080 Würzburg, Germany
| | - Annette Berbner
- Department of Internal Medicine, Cardiology, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080 Würzburg, Germany
| | - Paula-Anahi Arias-Loza
- Department of Internal Medicine, Cardiology, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080 Würzburg, Germany
| | - Tatjana Williams
- Department of Internal Medicine, Cardiology, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080 Würzburg, Germany
| | - Mathias Kaspar
- Comprehensive Heart Failure Center, University of Würzburg, Straubmühlweg 2a, 97078 Würzburg, Germany
| | - Martin Czolbe
- Department of Internal Medicine, Cardiology, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080 Würzburg, Germany
| | - Jennifer Q Kwong
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, 240 Albert Sabin Way, MLC 7020 Cincinnati, OH 45229, USA
| | - Jeffery D Molkentin
- Division of Molecular Cardiovascular Biology, Cincinnati Children's Hospital Medical Center, 240 Albert Sabin Way, MLC 7020 Cincinnati, OH 45229, USA
| | - Katrin Gertrud Heinze
- Rudolf Virchow Center for Experimental Biomedicine, University of Würzburg, Josef-Schneider-Str. 2, 97080 Würzburg, Germany
| | - Elena N Dedkova
- Department of Pharmacology, School of Medicine, University of California Davis, 451 E. Health Sciences Drive, Genome and Biomedical Sciences Facility, Davis, CA 95616, USA
| | - Oliver Ritter
- Department of Internal Medicine, Cardiology, University Hospital Würzburg, Oberdürrbacherstr. 6, 97080 Würzburg, Germany Comprehensive Heart Failure Center, University of Würzburg, Straubmühlweg 2a, 97078 Würzburg, Germany Medizinische Hochschule Brandenburg, Campus Klinikum Brandenburg/Havel, Abteilung für Kardiologie und Pneumologie, Hochstr. 29, 14770 Brandenburg an der Havel, Germany
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13
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Chweih H, Castilho RF, Figueira TR. Tissue and sex specificities in Ca2+handling by isolated mitochondria in conditions avoiding the permeability transition. Exp Physiol 2015; 100:1073-92. [DOI: 10.1113/ep085248] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 06/05/2015] [Indexed: 12/12/2022]
Affiliation(s)
- Hanan Chweih
- Department of Clinical Pathology; Faculty of Medical Sciences; State University of Campinas; Campinas Brazil
| | - Roger F. Castilho
- Department of Clinical Pathology; Faculty of Medical Sciences; State University of Campinas; Campinas Brazil
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14
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Tewari SG, Camara AKS, Stowe DF, Dash RK. Computational analysis of Ca2+ dynamics in isolated cardiac mitochondria predicts two distinct modes of Ca2+ uptake. J Physiol 2014; 592:1917-30. [PMID: 24591571 DOI: 10.1113/jphysiol.2013.268847] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Cardiac mitochondria can act as a significant Ca(2+) sink and shape cytosolic Ca(2+) signals affecting various cellular processes, such as energy metabolism and excitation-contraction coupling. However, different mitochondrial Ca(2+) uptake mechanisms are still not well understood. In this study, we analysed recently published Ca(2+) uptake experiments performed on isolated guinea pig cardiac mitochondria using a computer model of mitochondrial bioenergetics and cation handling. The model analyses of the data suggest that the majority of mitochondrial Ca(2+) uptake, at physiological levels of cytosolic Ca(2+) and Mg(2+), occurs through a fast Ca(2+) uptake pathway, which is neither the Ca(2+) uniporter nor the rapid mode of Ca(2+) uptake. This fast Ca(2+) uptake component was explained by including a biophysical model of the ryanodine receptor (RyR) in the computer model. However, the Mg(2+)-dependent enhancement of the RyR adaptation was not evident in this RyR-type channel, in contrast to that of cardiac sarcoplasmic reticulum RyR. The extended computer model is corroborated by simulating an independent experimental dataset, featuring mitochondrial Ca(2+) uptake, egress and sequestration. The model analyses of the two datasets validate the existence of two classes of Ca(2+) buffers that comprise the mitochondrial Ca(2+) sequestration system. The modelling study further indicates that the Ca(2+) buffers respond differentially depending on the source of Ca(2+) uptake. In particular, it suggests that the Class 1 Ca(2+) buffering capacity is auto-regulated by the rate at which Ca(2+) is taken up by mitochondria.
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Affiliation(s)
- Shivendra G Tewari
- Biotechnology and Bioengineering Center, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, WI 53226-6509, USA.
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15
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Ivannikov MV, Macleod GT. Mitochondrial free Ca²⁺ levels and their effects on energy metabolism in Drosophila motor nerve terminals. Biophys J 2014; 104:2353-61. [PMID: 23746507 DOI: 10.1016/j.bpj.2013.03.064] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2012] [Revised: 02/24/2013] [Accepted: 03/25/2013] [Indexed: 01/29/2023] Open
Abstract
Mitochondrial Ca²⁺ uptake exerts dual effects on mitochondria. Ca²⁺ accumulation in the mitochondrial matrix dissipates membrane potential (ΔΨm), but Ca²⁺ binding of the intramitochondrial enzymes accelerates oxidative phosphorylation, leading to mitochondrial hyperpolarization. The levels of matrix free Ca²⁺ ([Ca²⁺]m) that trigger these metabolic responses in mitochondria in nerve terminals have not been determined. Here, we estimated [Ca²⁺]m in motor neuron terminals of Drosophila larvae using two methods: the relative responses of two chemical Ca²⁺ indicators with a 20-fold difference in Ca²⁺ affinity (rhod-FF and rhod-5N), and the response of a low-affinity, genetically encoded ratiometric Ca²⁺ indicator (D4cpv) calibrated against known Ca²⁺ levels. Matrix pH (pHm) and ΔΨm were monitored using ratiometric pericam and tetramethylrhodamine ethyl ester probe, respectively, to determine when mitochondrial energy metabolism was elevated. At rest, [Ca²⁺]m was 0.22 ± 0.04 μM, but it rose to ~26 μM (24.3 ± 3.4 μM with rhod-FF/rhod-5N and 27.0 ± 2.6 μM with D4cpv) when the axon fired close to its endogenous frequency for only 2 s. This elevation in [Ca²⁺]m coincided with a rapid elevation in pHm and was followed by an after-stimulus ΔΨm hyperpolarization. However, pHm decreased and no ΔΨm hyperpolarization was observed in response to lower levels of [Ca²⁺]m, up to 13.1 μM. These data indicate that surprisingly high levels of [Ca²⁺]m are required to stimulate presynaptic mitochondrial energy metabolism.
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Affiliation(s)
- Maxim V Ivannikov
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
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16
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Lotz C, Lin AJ, Black CM, Zhang J, Lau E, Deng N, Wang Y, Zong NC, Choi JH, Xu T, Liem DA, Korge P, Weiss JN, Hermjakob H, Yates JR, Apweiler R, Ping P. Characterization, design, and function of the mitochondrial proteome: from organs to organisms. J Proteome Res 2013; 13:433-46. [PMID: 24070373 DOI: 10.1021/pr400539j] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Mitochondria are a common energy source for organs and organisms; their diverse functions are specialized according to the unique phenotypes of their hosting environment. Perturbation of mitochondrial homeostasis accompanies significant pathological phenotypes. However, the connections between mitochondrial proteome properties and function remain to be experimentally established on a systematic level. This uncertainty impedes the contextualization and translation of proteomic data to the molecular derivations of mitochondrial diseases. We present a collection of mitochondrial features and functions from four model systems, including two cardiac mitochondrial proteomes from distinct genomes (human and mouse), two unique organ mitochondrial proteomes from identical genetic codons (mouse heart and mouse liver), as well as a relevant metazoan out-group (drosophila). The data, composed of mitochondrial protein abundance and their biochemical activities, capture the core functionalities of these mitochondria. This investigation allowed us to redefine the core mitochondrial proteome from organs and organisms, as well as the relevant contributions from genetic information and hosting milieu. Our study has identified significant enrichment of disease-associated genes and their products. Furthermore, correlational analyses suggest that mitochondrial proteome design is primarily driven by cellular environment. Taken together, these results connect proteome feature with mitochondrial function, providing a prospective resource for mitochondrial pathophysiology and developing novel therapeutic targets in medicine.
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Affiliation(s)
- Christopher Lotz
- Departments of Physiology and Medicine/Division of Cardiology, David Geffen School of Medicine at UCLA , 675 Charles E. Young Drive, MRL Building, Suite 1609, Los Angeles, California 90095, United States
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17
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Yamanaka R, Shindo Y, Hotta K, Suzuki K, Oka K. NO/cGMP/PKG signaling pathway induces magnesium release mediated by mitoKATP channel opening in rat hippocampal neurons. FEBS Lett 2013; 587:2643-8. [PMID: 23831575 DOI: 10.1016/j.febslet.2013.06.049] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 06/26/2013] [Accepted: 06/26/2013] [Indexed: 11/19/2022]
Abstract
Intracellular Mg²⁺ concentration ([Mg²⁺]i) and NO regulate cell survival and death. To reveal the involvement of NO in intracellular Mg²⁺ regulation, we visualized intracellular Mg²⁺ using the fluorescent Mg²⁺ indicator KMG-104-AM in rat hippocampal neurons. Pharmacological experiments using SNAP, 8-Br-cGMP, diazoxide and several inhibitors revealed that the NO/cGMP/Protein kinsase G (PKG) signaling pathway triggers an increase in [Mg²⁺]i, and that Mg²⁺ mobilization is due to Mg²⁺ release from mitochondria induced by mitoKATP channel opening. In addition, Mg²⁺ release is potentiated by the positive feedback loop including mitoKATP channel opening, mitochondrial depolarization and PKC activation.
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Affiliation(s)
- Ryu Yamanaka
- Center for Biosciences and Informatics, School of Fundamental Science and Technology, Keio University, Yokohama, Kanagawa, Japan
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18
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Csordás G, Golenár T, Seifert EL, Kamer KJ, Sancak Y, Perocchi F, Moffat C, Weaver D, Perez SDLF, Bogorad R, Koteliansky V, Adijanto J, Mootha VK, Hajnóczky G. MICU1 controls both the threshold and cooperative activation of the mitochondrial Ca²⁺ uniporter. Cell Metab 2013; 17:976-987. [PMID: 23747253 PMCID: PMC3722067 DOI: 10.1016/j.cmet.2013.04.020] [Citation(s) in RCA: 377] [Impact Index Per Article: 34.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 04/02/2013] [Accepted: 04/26/2013] [Indexed: 12/18/2022]
Abstract
Mitochondrial Ca(2+) uptake via the uniporter is central to cell metabolism, signaling, and survival. Recent studies identified MCU as the uniporter's likely pore and MICU1, an EF-hand protein, as its critical regulator. How this complex decodes dynamic cytoplasmic [Ca(2+)] ([Ca(2+)]c) signals, to tune out small [Ca(2+)]c increases yet permit pulse transmission, remains unknown. We report that loss of MICU1 in mouse liver and cultured cells causes mitochondrial Ca(2+) accumulation during small [Ca(2+)]c elevations but an attenuated response to agonist-induced [Ca(2+)]c pulses. The latter reflects loss of positive cooperativity, likely via the EF-hands. MICU1 faces the intermembrane space and responds to [Ca(2+)]c changes. Prolonged MICU1 loss leads to an adaptive increase in matrix Ca(2+) binding, yet cells show impaired oxidative metabolism and sensitization to Ca(2+) overload. Collectively, the data indicate that MICU1 senses the [Ca(2+)]c to establish the uniporter's threshold and gain, thereby allowing mitochondria to properly decode different inputs.
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Affiliation(s)
- György Csordás
- Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Tünde Golenár
- Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Erin L Seifert
- Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Kimberli J Kamer
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA
| | - Yasemin Sancak
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Systems Biology, Harvard Medical School and Broad Institute, Cambridge, MA 02142, USA
| | - Fabiana Perocchi
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Systems Biology, Harvard Medical School and Broad Institute, Cambridge, MA 02142, USA; Gene Center, Ludwig-Maximilians-Universität, Munich D-81377, Germany
| | - Cynthia Moffat
- Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - David Weaver
- Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Sergio de la Fuente Perez
- Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Roman Bogorad
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | | | - Jeffrey Adijanto
- Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA
| | - Vamsi K Mootha
- Department of Molecular Biology, Massachusetts General Hospital, Boston, MA 02114, USA; Department of Systems Biology, Harvard Medical School and Broad Institute, Cambridge, MA 02142, USA.
| | - György Hajnóczky
- Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, PA 19107, USA.
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19
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Boelens AD, Pradhan RK, Blomeyer CA, Camara AKS, Dash RK, Stowe DF. Extra-matrix Mg2+ limits Ca2+ uptake and modulates Ca2+ uptake-independent respiration and redox state in cardiac isolated mitochondria. J Bioenerg Biomembr 2013; 45:203-18. [PMID: 23456198 DOI: 10.1007/s10863-013-9500-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Accepted: 01/24/2013] [Indexed: 12/20/2022]
Abstract
Cardiac mitochondrial matrix (m) free Ca(2+) ([Ca(2+)]m) increases primarily by Ca(2+) uptake through the Ca(2+) uniporter (CU). Ca(2+) uptake via the CU is attenuated by extra-matrix (e) Mg(2+) ([Mg(2+)]e). How [Ca(2+)]m is dynamically modulated by interacting physiological levels of [Ca(2+)]e and [Mg(2+)]e and how this interaction alters bioenergetics are not well understood. We postulated that as [Mg(2+)]e modulates Ca(2+) uptake via the CU, it also alters bioenergetics in a matrix Ca(2+)-induced and matrix Ca(2+)-independent manner. To test this, we measured changes in [Ca(2+)]e, [Ca(2+)]m, [Mg(2+)]e and [Mg(2+)]m spectrofluorometrically in guinea pig cardiac mitochondria in response to added CaCl2 (0-0.6 mM; 1 mM EGTA buffer) with/without added MgCl2 (0-2 mM). In parallel, we assessed effects of added CaCl2 and MgCl2 on NADH, membrane potential (ΔΨm), and respiration. We found that ≥0.125 mM MgCl2 significantly attenuated CU-mediated Ca(2+) uptake and [Ca(2+)]m. Incremental [Mg(2+)]e did not reduce initial Ca(2+)uptake but attenuated the subsequent slower Ca(2+) uptake, so that [Ca(2+)]m remained unaltered over time. Adding CaCl2 without MgCl2 to attain a [Ca(2+)]m from 46 to 221 nM enhanced state 3 NADH oxidation and increased respiration by 15 %; up to 868 nM [Ca(2+)]m did not additionally enhance NADH oxidation or respiration. Adding MgCl2 did not increase [Mg(2+)]m but it altered bioenergetics by its direct effect to decrease Ca(2+) uptake. However, at a given [Ca(2+)]m, state 3 respiration was incrementally attenuated, and state 4 respiration enhanced, by higher [Mg(2+)]e. Thus, [Mg(2+)]e without a change in [Mg(2+)]m can modulate bioenergetics independently of CU-mediated Ca(2+) transport.
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Affiliation(s)
- Age D Boelens
- Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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20
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Singh H, Jalodia S, Gupta MS, Talapatra P, Gupta V, Singh I. Role of magnesium sulfate in neuroprotection in acute ischemic stroke. Ann Indian Acad Neurol 2012; 15:177-80. [PMID: 22919188 PMCID: PMC3424793 DOI: 10.4103/0972-2327.99705] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2011] [Revised: 11/13/2011] [Accepted: 01/08/2012] [Indexed: 11/08/2022] Open
Abstract
AIMS To study the effect of intravenous magnesium sulfate infusion on clinical outcome of patients of acute stroke. MATERIALS AND METHODS Sixty consecutive cases of acute ischemic stroke hospitalised within 24 h of an episode of stroke were taken as subjects. All subjects underwent a computed tomography head, and those found to have evidence of bleed/space-occupying lesions were excluded from the study. The subjects taken up for the study were divided into two groups of 30 subjects each. Both the groups received the standard protocol management for acute ischemic stroke. Subjects of Group 1 additionally received intravenous magnesium sulfate as initial 4 g bolus dose over 15 min followed by 16 g as slow infusion over the next 24 h. In all the subjects of the two study groups, serum magnesium levels were estimated at the time of admission (Day 0), Day 1 and Day 2 of hospitalization using an atomic absorption spectrometer. STATISTICAL ANALYSIS USED Scandinavian stroke scores were calculated on Day 3, day of discharge and Day 28. Paired t-test was employed for comparison of stroke scores on Day 3, day of discharge and Day 28 within the same group and the unpaired t-test was used for the intergroup comparison, i.e. comparison of stroke scores of control group with corresponding stroke scores of magnesium group. RESULTS Comparison of stroke scores on Day 3 and day of discharge, on the day of discharge and Day 28 and on Day 3 and Day 28 in the magnesium group produced a t-value of 5.000 and P <0.001, which was highly significant. However, the comparison of the mean stroke scores between the magnesium and the control groups on Day 3, day of discharge and Day 28 yielded a P-value of >0.05, which was not significant. CONCLUSIONS The study failed to document a statistical significant stroke recovery in spite of achieving a significant rise in serum magnesium level, more than that necessary for neuroprotection, with an intravenous magnesium sulfate regime.
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Affiliation(s)
- Harpreet Singh
- Department of Medicine, Pandit B.D. Sharma Post Graduate Institute of Medical Sciences, Rohtak, Haryana, India
| | - Sunil Jalodia
- Department of Medicine, Pandit B.D. Sharma Post Graduate Institute of Medical Sciences, Rohtak, Haryana, India
| | - M. S. Gupta
- Department of Medicine, Pandit B.D. Sharma Post Graduate Institute of Medical Sciences, Rohtak, Haryana, India
| | - Paulomi Talapatra
- Department of Medicine, Pandit B.D. Sharma Post Graduate Institute of Medical Sciences, Rohtak, Haryana, India
| | - Vikas Gupta
- Department of Medicine, Pandit B.D. Sharma Post Graduate Institute of Medical Sciences, Rohtak, Haryana, India
| | - Ishwar Singh
- Department of Chemistry, M. D. University, Rohtak, Haryana, India
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21
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Afshari D, Moradian N, Rezaei M. Evaluation of the intravenous magnesium sulfate effect in clinical improvement of patients with acute ischemic stroke. Clin Neurol Neurosurg 2012; 115:400-4. [PMID: 22749947 DOI: 10.1016/j.clineuro.2012.06.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Revised: 05/03/2012] [Accepted: 06/02/2012] [Indexed: 11/26/2022]
Abstract
BACKGROUND Evidence is mounting that magnesium may play a critical role in the development of strokes and the healing process during and after a stroke. Magnesium is an N-methyl-D-aspartate (NMDA) glutamate receptor antagonist that has been shown to be neuroprotective in many preclinical models of ischemic and excitotoxic brain injury. This study was performed to evaluate the intravenous magnesium sulfate effect in clinical improvement of patients with acute ischemic stroke. METHODS One hundred and seven patients with acute ischemic stroke signs and symptoms lasting less than 12 hours were included in the study and were divided into two groups, 55 patients received 4 g of MgSO(4) over 15 minutes and then 16 g over the next 24 hours, and 52 patients were received matching placebo. The study primary end point was stroke related neurologic deficit evaluation by the national institute of stroke scale (NIHSS). RESULTS Patients receiving MgSO(4) showed significant recovery compared with the group of patients receiving placebo. CONCLUSION This study suggests that magnesium sulfate can be used as a safe and useful neuroprotective agent in acute ischemic stroke and lacunar stroke patients may represent a relevant and practical target population for agents with biological activity in white matter.
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Affiliation(s)
- Daryoush Afshari
- Neurology Department of Imam Reza Hospital, Kermanshah University of Medical Sciences, Kermanshah, Iran.
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22
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Sahota P, Savitz SI. Investigational therapies for ischemic stroke: neuroprotection and neurorecovery. Neurotherapeutics 2011; 8:434-51. [PMID: 21604061 PMCID: PMC3250280 DOI: 10.1007/s13311-011-0040-6] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Stroke is one of the leading causes of death and disability worldwide. Current treatment strategies for ischemic stroke primarily focus on reducing the size of ischemic damage and rescuing dying cells early after occurrence. To date, intravenous recombinant tissue plasminogen activator is the only United States Food and Drug Administration approved therapy for acute ischemic stroke, but its use is limited by a narrow therapeutic window. The pathophysiology of stroke is complex and it involves excitotoxicity mechanisms, inflammatory pathways, oxidative damage, ionic imbalances, apoptosis, angiogenesis, neuroprotection, and neurorestoration. Regeneration of the brain after damage is still active days and even weeks after a stroke occurs, which might provide a second window for treatment. A huge number of neuroprotective agents have been designed to interrupt the ischemic cascade, but therapeutic trials of these agents have yet to show consistent benefit, despite successful preceding animal studies. Several agents of great promise are currently in the middle to late stages of the clinical trial setting and may emerge in routine practice in the near future. In this review, we highlight select pharmacologic and cell-based therapies that are currently in the clinical trial stage for stroke.
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Affiliation(s)
- Preeti Sahota
- Department of Neurology, University of Texas Medical School at Houston, Houston, TX 77030 USA
| | - Sean I. Savitz
- Department of Neurology, University of Texas Medical School at Houston, Houston, TX 77030 USA
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23
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Wei AC, Liu T, Cortassa S, Winslow RL, O'Rourke B. Mitochondrial Ca2+ influx and efflux rates in guinea pig cardiac mitochondria: low and high affinity effects of cyclosporine A. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:1373-81. [PMID: 21362444 DOI: 10.1016/j.bbamcr.2011.02.012] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Revised: 02/14/2011] [Accepted: 02/17/2011] [Indexed: 12/12/2022]
Abstract
Ca(2+) plays a central role in energy supply and demand matching in cardiomyocytes by transmitting changes in excitation-contraction coupling to mitochondrial oxidative phosphorylation. Matrix Ca(2+) is controlled primarily by the mitochondrial Ca(2+) uniporter and the mitochondrial Na(+)/Ca(2+) exchanger, influencing NADH production through Ca(2+)-sensitive dehydrogenases in the Krebs cycle. In addition to the well-accepted role of the Ca(2+)-triggered mitochondrial permeability transition pore in cell death, it has been proposed that the permeability transition pore might also contribute to physiological mitochondrial Ca(2+) release. Here we selectively measure Ca(2+) influx rate through the mitochondrial Ca(2+) uniporter and Ca(2+) efflux rates through Na(+)-dependent and Na(+)-independent pathways in isolated guinea pig heart mitochondria in the presence or absence of inhibitors of mitochondrial Na(+)/Ca(2+) exchanger (CGP 37157) or the permeability transition pore (cyclosporine A). cyclosporine A suppressed the negative bioenergetic consequences (ΔΨ(m) loss, Ca(2+) release, NADH oxidation, swelling) of high extramitochondrial Ca(2+) additions, allowing mitochondria to tolerate total mitochondrial Ca(2+) loads of >400nmol/mg protein. For Ca(2+) pulses up to 15μM, Na(+)-independent Ca(2+) efflux through the permeability transition pore accounted for ~5% of the total Ca(2+) efflux rate compared to that mediated by the mitochondrial Na(+)/Ca(2+) exchanger (in 5mM Na(+)). Unexpectedly, we also observed that cyclosporine A inhibited mitochondrial Na(+)/Ca(2+) exchanger-mediated Ca(2+) efflux at higher concentrations (IC(50)=2μM) than those required to inhibit the permeability transition pore, with a maximal inhibition of ~40% at 10μM cyclosporine A, while having no effect on the mitochondrial Ca(2+) uniporter. The results suggest a possible alternative mechanism by which cyclosporine A could affect mitochondrial Ca(2+) load in cardiomyocytes, potentially explaining the paradoxical toxic effects of cyclosporine A at high concentrations. This article is part of a Special Issue entitled: Mitochondria and Cardioprotection.
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Affiliation(s)
- An-Chi Wei
- Department of Biomedical Engineering, Institute of Computational Medicine, The Johns Hopkins University, Baltimore MD 21205-2195, USA
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24
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MICU1 encodes a mitochondrial EF hand protein required for Ca(2+) uptake. Nature 2010; 467:291-6. [PMID: 20693986 PMCID: PMC2977980 DOI: 10.1038/nature09358] [Citation(s) in RCA: 681] [Impact Index Per Article: 48.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2010] [Accepted: 07/19/2010] [Indexed: 02/07/2023]
Abstract
Mitochondrial calcium uptake plays a central role in cell physiology by stimulating ATP production, shaping cytosolic calcium transients, and regulating cell death. The biophysical properties of mitochondrial calcium uptake have been studied in detail, but the underlying proteins remain elusive. Here, we utilize an integrative strategy to predict human genes involved in mitochondrial calcium entry based on clues from comparative physiology, evolutionary genomics, and organelle proteomics. RNA interference against 13 top candidates highlighted one gene that we now call mitochondrial calcium uptake 1 (MICU1). Silencing MICU1 does not disrupt mitochondrial respiration or membrane potential but abolishes mitochondrial calcium entry in intact and permeabilized cells, and attenuates the metabolic coupling between cytosolic calcium transients and activation of matrix dehydrogenases. MICU1 is associated with the organelle’s inner membrane and has two canonical EF hands that are essential for its activity, suggesting a role in calcium sensing. MICU1 represents the founding member of a set of proteins required for high capacity mitochondrial calcium entry. Its discovery may lead to the complete molecular characterization of mitochondrial calcium uptake pathways, and offers genetic strategies for understanding their contribution to normal physiology and disease.
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25
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Santo-Domingo J, Demaurex N. Calcium uptake mechanisms of mitochondria. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2010; 1797:907-12. [PMID: 20079335 DOI: 10.1016/j.bbabio.2010.01.005] [Citation(s) in RCA: 227] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2009] [Revised: 01/06/2010] [Accepted: 01/08/2010] [Indexed: 12/16/2022]
Abstract
The ability of mitochondria to capture Ca2+ ions has important functional implications for cells, because mitochondria shape cellular Ca2+ signals by acting as a Ca2+ buffer and respond to Ca2+ elevations either by increasing the cell energy supply or by triggering the cell death program of apoptosis. A mitochondrial Ca2+ channel known as the uniporter drives the rapid and massive entry of Ca2+ ions into mitochondria. The uniporter operates at high, micromolar cytosolic Ca2+ concentrations that are only reached transiently in cells, near Ca2+ release channels. Mitochondria can also take up Ca2+ at low, nanomolar concentrations, but this high affinity mode of Ca2+ uptake is not well characterized. Recently, leucine-zipper-EF hand-containing transmembrane region (Letm1) was proposed to be an electrogenic 1:1 mitochondrial Ca2+/H+ antiporter that drives the uptake of Ca2+ into mitochondria at nanomolar cytosolic Ca2+ concentrations. In this article, we will review the properties of the Ca2+ import systems of mitochondria and discuss how Ca2+ uptake via an electrogenic 1:1 Ca2+/H+ antiport challenges our current thinking of the mitochondrial Ca2+ uptake mechanism.
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Affiliation(s)
- Jaime Santo-Domingo
- Department of Cell Physiology and Metabolism, University of Geneva, 1, rue Michel-Servet, CH-1211 Geneva 4, Switzerland
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Wadhwa A, Sengupta P, Durrani J, Akça O, Lenhardt R, Sessler DI, Doufas AG. Magnesium sulphate only slightly reduces the shivering threshold in humans. Br J Anaesth 2005; 94:756-62. [PMID: 15749735 PMCID: PMC1361806 DOI: 10.1093/bja/aei105] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Hypothermia may be an effective treatment for stroke or acute myocardial infarction; however, it provokes vigorous shivering, which causes potentially dangerous haemodynamic responses and prevents further hypothermia. Magnesium is an attractive anti-shivering agent because it is used for treatment of postoperative shivering and provides protection against ischaemic injury in animal models. We tested the hypothesis that magnesium reduces the threshold (triggering core temperature) and gain of shivering without substantial sedation or muscle weakness. METHODS We studied nine healthy male volunteers (18-40 yr) on two randomly assigned treatment days: (1) control and (2) magnesium (80 mg kg(-1) followed by infusion at 2 g h(-1)). Lactated Ringer's solution (4 degrees C) was infused via a central venous catheter over a period of approximately 2 h to decrease tympanic membrane temperature by approximately 1.5 degrees C h(-1). A significant and persistent increase in oxygen consumption identified the threshold. The gain of shivering was determined by the slope of oxygen consumption vs core temperature regression. Sedation was evaluated using a verbal rating score (VRS) from 0 to 10 and bispectral index (BIS) of the EEG. Peripheral muscle strength was evaluated using dynamometry and spirometry. Data were analysed using repeated measures anova; P<0.05 was statistically significant. RESULTS Magnesium reduced the shivering threshold (36.3 [SD 0.4] degrees C vs 36.6 [0.3] degrees C, P = 0.040). It did not affect the gain of shivering (control, 437 [289] ml min(-1) degrees C(-1); magnesium, 573 [370] ml min(-1) degrees C(-1); P=0.344). The magnesium bolus did not produce significant sedation or appreciably reduce muscle strength. CONCLUSIONS Magnesium significantly reduced the shivering threshold. However, in view of the modest absolute reduction, this finding is considered to be clinically unimportant for induction of therapeutic hypothermia.
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Affiliation(s)
- Anupama Wadhwa
- Assistant Professor, OUTCOMES RESEARCH™ Institute and Department of Anesthesiology and Perioperative Medicine, University of Louisville
| | - Papiya Sengupta
- Research Fellow, OUTCOMES RESEARCH™ Institute, University of Louisville
| | - Jaleel Durrani
- Resident, Department of Anesthesiology and Perioperative Medicine, University of Louisville
| | - Ozan Akça
- Assistant Director OUTCOMES RESEARCH™ Institute, Assistant Professor Department of Anesthesiology and Perioperative Medicine, Director Neurosciences Intensive Care Unit, University of Louisville
| | - Rainer Lenhardt
- Assistant Director OUTCOMES RESEARCH™ Institute, Assistant Professor Department of Anesthesiology and Perioperative Medicine, Director Neurosciences Intensive Care Unit, University of Louisville
| | - Daniel I. Sessler
- Vice Dean for Research, Associate Vice President for Health Affairs, Director OUTCOMES RESEARCH™ Institute, Lolita & Samuel Weakley Distinguished University Research Chair, Professor of Anesthesiology and Pharmacology, University of Louisville
| | - Anthony G. Doufas
- Assistant Professor and Director of Research, Department of Anesthesiology and Perioperative Medicine and OUTCOMES RESEARCH™ Institute, University of Louisville
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Abstract
Magnesium is involved in multiple physiological processes that may be relevant to cerebral ischaemia, including antagonism of glutamate release, NMDA receptor blockade, calcium channel antagonism, and maintenance of cerebral blood flow. Systemically administered magnesium at doses that double physiological serum concentration significantly reduces infarct volume in animal models of stroke, with a window of up to six hours after onset and favourable dose-response characteristics when compared with previously tested neuroprotective agents. Small clinical trials have reported benefit, but results are not statistically significant in systematic review. A large ongoing trial (IMAGES) will report in 2003-4 and further trials are planned.
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Affiliation(s)
- K W Muir
- University Department of Neurology, Institute of Neurological Sciences, Southern General Hospital, Glasgow, UK.
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Saatman KE, Bareyre FM, Grady MS, McIntosh TK. Acute cytoskeletal alterations and cell death induced by experimental brain injury are attenuated by magnesium treatment and exacerbated by magnesium deficiency. J Neuropathol Exp Neurol 2001; 60:183-94. [PMID: 11273006 DOI: 10.1093/jnen/60.2.183] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Traumatic brain injury results in a profound decline in intracellular magnesium ion levels that may jeopardize critical cellular functions. We examined the consequences of preinjury magnesium deficiency and post-traumatic magnesium treatment on injury-induced cytoskeletal damage and cell death at 24 h after injury. Adult male rats were fed either a normal (n = 24) or magnesium-deficient diet (n = 16) for 2 wk prior to anesthesia and lateral fluid percussion brain injury (n = 31) or sham injury (n = 9). Normally fed animals were then randomized to receive magnesium chloride (125 micromol, i.v., n = 10) or vehicle solution (n = 11) at 10 min postinjury. Magnesium treatment reduced cortical cell loss (p < 0.05), cortical alterations in microtubule-associated protein-2 (MAP-2) (p < 0.05), and both cortical and hippocampal calpain-mediated spectrin breakdown (p < 0.05 for each region) when compared to vehicle treatment. Conversely, magnesium deficiency prior to brain injury led to a greater area of cortical cell loss (p < 0.05 compared to vehicle treatment). Moreover, brain injury to magnesium-deficient rats resulted in cytoskeletal alterations within the cortex and hippocampus that were not observed in vehicle- or magnesium-treated animals. These data suggest that cortical cell death and cytoskeletal disruptions in cortical and hippocampal neurons may be sensitive to magnesium status after experimental brain injury, and may be mediated in part through modulation of calpains.
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Affiliation(s)
- K E Saatman
- Department of Neurosurgery, School of Medicine, University of Pennsylvania, Philadelphia 19104, USA
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Lampl Y, Gilad R, Geva D, Eshel Y, Sadeh M. Intravenous administration of magnesium sulfate in acute stroke: a randomized double-blind study. Clin Neuropharmacol 2001; 24:11-5. [PMID: 11290876 DOI: 10.1097/00002826-200101000-00003] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A randomized, placebo-controlled, double-blind study was performed as a pilot study to examine the benefit of the administration of magnesium sulfate given intravenously as a protective substance during the first 24 hours following a stroke. Patients who had cortical infarction in the middle cerebral artery territory with moderate to severe neurologic deficits lasting for more than 15 minutes with onset less than 24 hours were included. The patients were treated with magnesium sulfate or placebo for 5 days and examined by a blinded investigator. Patients had follow-up for 30 days. The primary efficacy variable was the proportion of patients reaching mild to moderate neurologic deficit on the Orgogozo scale (80 points) and relative functional independence on the Barthel index (60 points). Orgogozo scale and Mathew scale values were obtained on admission and days 2, 4, 8, and 30 after stroke. Barthel activities of daily living index and Rankin disability score were obtained on day 30. Forty-one patients (22 given treatment and 19 given placebo) demonstrated significant beneficial effects on the Orgogozo scale (84 +/- 11 vs. 64 +/- 10, p < 0.0001) and (83 +/- 14 vs. 70 +/- 15, p < 0.009), respectively. At the end of 1-month follow-up, the Barthel ADL index was nonsignificantly higher and the Rankin disability score was marginally significantly lower in the magnesium-treated group (84 +/- 26 vs. 71.8 +/- 26, p < 0.143) than in control subjects (2.3 +/- 1.1 vs. 3 +/- 1.3, p < 0.077). Intravenous magnesium sulfate had significant positive effect on the outcome in patients with acute stroke. Further studies on a larger scale are needed to confirm these findings.
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Affiliation(s)
- Y Lampl
- Department of Neurology, Edith Wolfson Medical Center, Holon, Israel
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30
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Muir KW. Therapeutic potential of magnesium in the treatment of acute stroke. J Stroke Cerebrovasc Dis 2000. [DOI: 10.1053/jscd.2000.20669] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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Tofukuji M, Matsuda N, Dessy C, Morgan KG, Sellke FW. Intracellular free calcium accumulation in ferret vascular smooth muscle during crystalloid and blood cardioplegic infusions. J Thorac Cardiovasc Surg 1999; 118:163-72. [PMID: 10384199 DOI: 10.1016/s0022-5223(99)70155-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE The effects of magnesium- and potassium-based crystalloid and blood-containing cardioplegic solutions on coronary smooth muscle intracellular free calcium ([Ca2+]i) accumulation and microvascular contractile function were examined. METHODS Isolated ferret hearts were subjected to hyperkalemic (25 mmol/L K+) blood cardioplegic infusion, hypermagnesemic (25 mmol/L Mg2+, K+-free) crystalloid cardioplegic infusion, or hyperkalemic crystalloid cardioplegic infusion for 1 hour. Coronary arterioles were isolated, cannulated, and loaded with fura 2. Reactivity and [Ca2+]i were assessed with videomicroscopy. [Ca2+]i was measured at baseline and after application of 50 mmol/L KCl. In addition, [Ca2+]i and vascular contraction were measured during exposure to Mg2+ and K+ cardioplegic solution at both 4 degrees C and 37 degrees C. RESULTS From a baseline [Ca2+]i of 177 +/- 52 nmol/L, K+ cardioplegic infusion (302 +/- 80 nmol/L potassium) markedly increased [Ca2+]i, whereas blood cardioplegic infusion (214 +/- 53 nmol/L) and Mg2+ cardioplegic infusion (180 +/- 42 nmol/L) did not alter [Ca2+]i. Although a difference between groups in percentage contraction after application of 50 mmol/L KCl was not observed, [Ca2+]i increased significantly more in vessels in the control group (764 +/- 327 nmol/L) and the K+ crystalloid cardioplegic infusion group (698 +/- 215 nmol/L) than in vessels in the blood cardioplegic infusion group (402 +/- 45 nmol/L) and the Mg2+ cardioplegic infusion group (389 +/- 80 nmol/L). Mg2+ cardioplegic solution induced no microvascular contraction at either 4 degrees C or 37 degrees C, nor was an increase in [Ca2+]i observed. K+ cardioplegic solution induced microvascular contraction at 37 degrees C but not at 4 degrees C; it increased [Ca2+]i at both 4 degrees C and 37 degrees C. CONCLUSION An Mg2+-based cardioplegic solution, or appropriate Mg2+ or blood supplementation of a K+ crystalloid cardioplegic solution, may decrease the accumulation of [Ca2+]i in the vascular smooth muscle during ischemic arrest.
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Affiliation(s)
- M Tofukuji
- Division of Cardiothoracic Surgery, Department of Surgery, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston Biomedical Research Institute, Boston, MA, USA
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Abstract
BACKGROUND AND PURPOSE Parenterally administered MgSO4 is neuroprotective in standard animal models of focal cerebral ischemia and in many other paradigms of brain injury. Previous small clinical trials in stroke patients have explored the safety and tolerability of different infusion regimens. This study was undertaken to optimize the regimen for a multicenter trial. METHODS Within 24 hours of the onset of clinically diagnosed stroke, patients were randomized to receive placebo or one of three intravenous MgSO4 infusions: a loading infusion of 8, 12, or 16 mmol, followed by 65 mmol over 24 hours. Cardiovascular parameters, serum magnesium concentrations, and blood glucose concentrations were determined. Outcome at 30 and 90 days was recorded. RESULTS Twenty-five patients were recruited and treated at a mean time of 20 hours after stroke. No tolerability problems were identified. No effects of magnesium on heart rate, blood pressure, or blood glucose were evident. Serum magnesium concentrations rose to target levels most rapidly in the highest loading infusion group and were maintained in all groups for at least 24 hours. CONCLUSIONS MgSO4 infusions that rapidly elevate the serum magnesium concentration to potentially therapeutic levels are well tolerated and have no major hemodynamic effects in patients with acute stroke. The 16-mmol loading infusion achieved target serum concentrations most rapidly and has been chosen for further trials.
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Affiliation(s)
- K W Muir
- University Department of Medicine and Therapeutics, Western Infirmary, Glasgow, Scotland.
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Steurer G, Yang P, Rao V, Mohl W, Glogar D, Smetana R. Acute myocardial infarction, reperfusion injury, and intravenous magnesium therapy: basic concepts and clinical implications. Am Heart J 1996; 132:478-82; discussion 496-502. [PMID: 8694007 DOI: 10.1016/s0002-8703(96)90339-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The concept of reperfusion-induced injury has aroused special interest during the past decade as thrombolysis and direct angioplasty were introduced for early restoration of coronary blood flow in patients with acute myocardial infarction. There is experimental and clinical evidence that oxygen-derived free radicals (oxyradical hypothesis), activation of the complement system (complement hypothesis), and disturbance in calcium homeostasis (calcium hypothesis), may account for the development of reperfusion injury. Data from numerous animal experiments and clinical trials suggest that magnesium, a physiologic calcium blocker, may be efficacious for reduction of reperfusion injury. Despite encouraging results from previous clinical trials that revealed beneficial effects of intravenous magnesium therapy with respect to mortality, left ventricular function, and infarct size, a recently published large-scale trial (ISIS-4) provided conflicting data and caused major controversy. Further clinical trials, well-designed and carefully conducted, should elucidate the beneficial effects of magnesium in acute myocardial infarction, especially in conjunction with new and aggressive reperfusion techniques.
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Affiliation(s)
- G Steurer
- Department of Cardiology, University of Vienna Medical School, Austria
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Tamm C, Papageorgiou I, Tardy I, Mermillod B, Rutishauser W, Lerch R. Effect of magnesium administered during postischemic reperfusion on myocardial oxidative metabolism in isolated rat hearts. Basic Res Cardiol 1994; 89:366-79. [PMID: 7826310 DOI: 10.1007/bf00795204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
To determine the effect of magnesium on myocardial function and oxidative metabolism after reperfusion, isolated rat hearts perfused retrogradely with erythrocyte-enriched medium (0.4 mM palmitate bound to 0.4 mM albumin, 11 mM glucose) were subjected to 60 minutes of no-flow ischemia followed by 60 minutes of reperfusion. Untreated postischemic hearts exhibited after 15 minutes of reperfusion recovery of myocardial oxygen consumption to 65% of the preischemic value despite persistent depression of left ventricular isovolumic pressure development to 21%. Magnesium (15 mM) administered during the initial 30 minutes of reperfusion reduced myocardial oxygen consumption of reperfuse myocardium by 35%. Oxidation of [1-14C]palmitate was slightly more reduced (-55%) than oxidation of [U-14C]glucose (-42%). Magnesium did not influence ultimate recovery of contractile function and cumulative myocardial release of creatine kinase. Thus, 15 mM magnesium administered during reperfusion elicited a reduction of oxidative metabolism. However, magnesium did not modify myocardial injury.
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Affiliation(s)
- C Tamm
- Cardiology Center, University Hospital, Geneva, Switzerland
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35
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Abstract
Extra and intracellular magnesium is involved in the control of myocardial calcium movements. Here we report on an increase in cytosolic calcium concentration in resting ventricular myocytes due to the withdrawal of extracellular magnesium under the condition of a blocked sodium-dependent calcium elimination. Evidence for an activation of cellular calcium efflux by extracellular magnesium showed experiments in perfused hearts. It is concluded that extracellular magnesium can modulate the intracellular free calcium concentration of the myocardial cells by its influence on calcium elimination.
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Affiliation(s)
- W Vierling
- Institut für Pharmakologie und Toxikologie, Technischen Universität München, Germany
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36
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Votyakova TV, Bazhenova EN, Zvjagilskaya RA. Yeast mitochondrial calcium uptake: regulation by polyamines and magnesium ions. J Bioenerg Biomembr 1993; 25:569-74. [PMID: 8132496 DOI: 10.1007/bf01108413] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Spermine, spermidine, and magnesium ions modulate the kinetic parameters of the Ca2+ transport system of Endomyces magnusii mitochondria. Mg2+ at concentrations up to 5 mM partially inhibits Ca2+ transport with a half-maximal inhibiting concentration of approximately 0.5 mM. In the presence of 2 mM MgCl2, the S0.5 value of the Ca2+ transport system increases from 220 to 490 microM, which indicates decreased affinity for the system. Spermine and spermidine exert an activating effect, having half-maximal concentrations of 12 and 50 microM, respectively. In the case of spermine, the S0.5 value falls to 50-65 microM, which implies an increase in the transport system affinity for Ca2+. Both Mg2+ and spermine cause a decrease of the Hill coefficient, giving evidence for a smaller degree of cooperativity. Spermine and spermidine enable yeast mitochondria to remove Ca2+ from the media completely. In contrast, Mg2+ lowers the mitochondrial buffer capacity. When both Mg2+ and spermine are present in the medium, their effects on the S0.5 value and the free extramitochondrial Ca2+ concentration are additive. The ability of spermine and Mg2+ to regulate yeast mitochondrial Ca2+ transport is discussed.
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Affiliation(s)
- T V Votyakova
- A. N. Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow
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37
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Yusuf S, Teo K, Woods K. Intravenous magnesium in acute myocardial infarction. An effective, safe, simple, and inexpensive intervention. Circulation 1993; 87:2043-6. [PMID: 8504519 DOI: 10.1161/01.cir.87.6.2043] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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Fox RM, Morgan RM, Markham A. Calcium antagonists and Bay K8644 promote depolarization of the rat heart mitochondrial membrane potential. Further evidence for a role in alteration of oxidative metabolism. Biochem Pharmacol 1993; 45:1995-2001. [PMID: 7685600 DOI: 10.1016/0006-2952(93)90009-l] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Studies were carried out using a tetraphenylphosphonium (TPP+)-selective electrode to monitor the effect of selected calcium (Ca2+) antagonists and the dihydropyridine Ca2+ agonist Bay K8644 on membrane potential (psi) associated with isolated rat heart mitochondria. Verapamil and diltiazem (10-500 microM), standard Ca2+ antagonists, produced a depolarization of both liver and heart mitochondria at concentrations > 150 microM. In contrast, nitrendipine (10-200 microM), a dihydropyridine compound, produced a concentration-related inhibition of psi in mitochondria from both sources, effects which were statistically significant at concentrations > 50 microM. Cinnarizine (10-100 microM) and bepridil (10-100 microM) also produced inhibition of heart psi, these effects being particularly noted in the presence of bepridil, where depolarization of the membrane was statistically significant with only 10 microM drug. The results indicate the complexity of action of these drugs at the mitochondrial level. In general, drug actions on psi appear to be correlated with previously reported effects on Ca2+ transportation rather than oxidative phosphorylation associated with rat heart mitochondria. The findings also illustrate that the mitochondrial actions of cardiovascular compounds may be of relevance in situ, particularly during ischaemia/reperfusion when mitochondria become loaded with Ca2+.
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Affiliation(s)
- R M Fox
- School of Health Sciences, University of Sunderland, Tyne and Wear, U.K
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Affiliation(s)
- K L Woods
- Department of Pharmacology and Therapeutics, University of Leicester
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40
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Brown PS, Holland FW, Parenteau GL, Clark RE. Magnesium ion is beneficial in hypothermic crystalloid cardioplegia. Ann Thorac Surg 1991; 51:359-66; discussion 367. [PMID: 1998412 DOI: 10.1016/0003-4975(91)90845-h] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The role of magnesium ion and its relation to the calcium concentration of cardioplegic solutions was reexamined in this study. Isolated rat hearts were used with an oxygenated modified Krebs-Henseleit bicarbonate buffer as perfusion medium. The hearts were arrested for 20 minutes at 37 degrees C or 90 minutes at 24 degrees C. Treatment groups received one dose of nine possible cardioplegic solutions containing magnesium (0, 1.2, or 15 mmol/L) and calcium (0.05, 1.5, or 4.5 mmol/L). Ninety-six percent of the 75 magnesium-treated hearts recovered, regardless of the calcium concentration, in contrast to a 52% recovery rate in the 69 hearts that did not receive magnesium. The addition of 15 mmol/L Mg2+ to a cardioplegic solution containing no magnesium but 0.05 mmol/L Ca2+ significantly increased (p less than 0.01) the percent recovery of the following parameters of cardiac function: systolic pressure, 74% to 93% (37 degrees C), 64% to 98% (24 degrees C); cardiac output, 76% to 101% (37 degrees C), 71% to 102% (24 degrees C); stroke work, 64% to 104% (37 degrees C), 52% to 99% (24 degrees C); and adenosine triphosphate level, 75% to 83% (37 degrees C), 58% to 90% (24 degrees C). There were significant reductions (p less than 0.03) in percent recovery (37 degrees C and 24 degrees C) of cardiac output, stroke work, and adenosine triphosphate level in the groups that contained 0 or 15 mmol/L Mg2+ as the calcium concentration was increased from 0.05 to 4.5 mmol/L.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- P S Brown
- Surgery Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, Maryland
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Tsuda T, Kogure K, Nishioka K, Watanabe T. Mg2+ administered up to twenty-four hours following reperfusion prevents ischemic damage of the Ca1 neurons in the rat hippocampus. Neuroscience 1991; 44:335-41. [PMID: 1944889 DOI: 10.1016/0306-4522(91)90058-v] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Inductively coupled plasma emission spectrometry analysis was applied to determine ischemia-induced changes of Mg2+ and Ca2+ in vulnerable regions of rat brain. This method can provide an accurate quantification and lower detection limits, as compared to atomic absorption spectrophotometry or several other methods. In the hippocampus, Mg2+ content significantly increases 24 h following 20 min of ischemia, followed by a gradual decrease between 48 and 72 h. Ca2+ accumulation was found at 48 and 72 h. At the cell membrane, Mg2+ plays a role as an endogenous calcium channel blocker of both the receptor-operated and voltage-dependent gates and, in the mitochondria, Mg2+ inhibits Ca2+ uptake processes. We propose that the mobilization of Mg2+ after 24 h reperfusion may counteract the process of ischemia-induced neuronal damage and that decreases of Mg2+ may be correlated with the degree of brain injury. However, in the natural concentration of Mg2+, the counteraction may not be sufficient for a neuroprotective effect. Therefore, after 24 h reperfusion, an artificial enhancement of Mg2+ is necessary for neuroprotection. In order to test the above hypothesis, MgCl2, (50 mM) was administered directly to the CA1 sector of the rat hippocampus before and at various intervals following 20 min of ischemia. Pyramidal cells were evaluated seven days later and neuronal density was determined. Consistent with the hypothesis, a neuroprotective effect was observed, even when MgCl2 was administered 24 h, but not 48 h, after the ischemic episode.
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Affiliation(s)
- T Tsuda
- Department of Neurology, Institute of Brain Disease, Sendai, Japan
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Rasmussen HS, Thomsen PE. The electrophysiological effects of intravenous magnesium on human sinus node, atrioventricular node, atrium, and ventricle. Clin Cardiol 1989; 12:85-90. [PMID: 2653679 DOI: 10.1002/clc.4960120204] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The effects of intravenously (IV) administered magnesium chloride (MgCl) on electrophysiologic and electrocardiographic variables were studied in 13 patients undergoing a routine electrophysiologic assessment for clinical indications. An infusion of 12 mmol of MgCl was given during a 10-min period and relevant electrophysiologic variables were determined before and after the infusion. Serum Mg levels increased from 0.78 +/- 0.03 (mean +/- SEM) before to 1.52 +/- 0.08 ms after the infusion (p less than 0.0001). Magnesium treatment caused a significant prolongation in PR interval (from 151 +/- 8 to 174 +/- 8 ms, p less than 0.001) as well as in QRS duration (from 90 +/- 4 to 101 +/- 6 ms, p less than 0.05). Likewise, intra-atrial (PA) as well as atrioventricular (AV) nodal (AH) conduction times were significantly prolonged (from 33 +/- 3 to 46 +/- 3 ms, p less than 0.01, and from 85 +/- 6 to 94 +/- 6 ms, p less than 0.05, respectively). Mean effective and functional atrial refractory periods increased (from 228 +/- 8 to 256 +/- 10 ms, p less than 0.01 and from 292 +/- 9 to 320 +/- 11 ms, p less than 0.01, respectively), as did mean AV node functional refractory period (from 399 +/- 29 to 422 +/- 27 ms, p less than 0.02). No significant change occurred with regard to sinus node function (as estimated from heart rate, sinus node recovery time, and calculated sinoatrial conduction time) or ventricular refractoriness. It is concluded that IV Mg has several electrophysiologic effects that may be beneficial in the treatment/prevention of supraventricular tachyarrhythmias.
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Affiliation(s)
- H S Rasmussen
- Department of Cardiology/Cardiovascular Laboratorium, Aarhus Municipal Hospital, University of Aarhus, Denmark
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Rizzuto R, Bernardi P, Favaron M, Azzone GF. Pathways for Ca2+ efflux in heart and liver mitochondria. Biochem J 1987; 246:271-7. [PMID: 3689311 PMCID: PMC1148273 DOI: 10.1042/bj2460271] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
1. Two processes of Ruthenium Red-insensitive Ca2+ efflux exist in liver and in heart mitochondria: one Na+-independent, and another Na+-dependent. The processes attain maximal rates of 1.4 and 3.0 nmol of Ca2+.min-1.mg-1 for the Na+-dependent and 1.2 and 2.0 nmol of Ca2+.min-1.mg-1 for the Na+-independent, in liver and heart mitochondria, respectively. 2. The Na+-dependent pathway is inhibited, both in heart and in liver mitochondria, by the Ca2+ antagonist diltiazem with a Ki of 4 microM. The Na+-independent pathway is inhibited by diltiazem with a Ki of 250 microM in liver mitochondria, while it behaves as almost insensitive to diltiazem in heart mitochondria. 3. Stretching of the mitochondrial inner membrane in hypo-osmotic media results in activation of the Na+-independent pathway both in liver and in heart mitochondria. 4. Both in heart and liver mitochondria the Na+-independent pathway is insensitive to variations of medium pH around physiological values, while the Na+-dependent pathway is markedly stimulated parallel with acidification of the medium. The pH-activated, Na+-dependent pathway maintains the diltiazem sensitivity. 5. In heart mitochondria, the Na+-dependent pathway is non-competitively inhibited by Mg2+ with a Ki of 0.27 mM, while the Na+-independent pathway is less affected; similarly, in liver mitochondria Mg2+ inhibits the Na+-dependent pathway more than it does the Na+-independent pathway. In the presence of physiological concentrations of Na+, Ca2+ and Mg2+, the Na+-independent and the Na+-dependent pathways operate at rates, respectively, of 0.5 and 1.0 nmol of Ca2+.min-1.mg-1 in heart mitochondria and 0.9 and 0.2 nmol of Ca2+.min-1.mg-1 in liver mitochondria. It is concluded that both heart and liver mitochondria possess two independent pathways for Ca2+ efflux operating at comparable rates.
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Affiliation(s)
- R Rizzuto
- C.N.R. Unit for the Study of Physiology of Mitochondria, University of Padova, Italy
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44
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Zwerling HK. Does exogenous magnesium suppress myocardial irritability and tachyarrhythmias in the nondigitalized patient? Am Heart J 1987; 113:1046-53. [PMID: 3031970 DOI: 10.1016/0002-8703(87)90078-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Lukács GL, Fonyó A. The Ba2+ sensitivity of the Na+-induced Ca2+ efflux in heart mitochondria: the site of inhibitory action. BIOCHIMICA ET BIOPHYSICA ACTA 1986; 858:125-34. [PMID: 3707957 DOI: 10.1016/0005-2736(86)90298-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The Na+-induced Ca2+ release from rat heart mitochondria was measured in the presence of Ruthenium red. Ba2+ effectively inhibited the Na+-induced Ca2+ release. At 10 mM Na+ 50% inhibition was reached by 1.51 +/- 0.48 (S.D., n = 8) microM Ba2+ in the presence of 0.1 mg/ml albumin and by 0.87 +/- 0.25 (S.D., n = 3) microM Ba2+ without albumin. In order to inhibit, it was not required that Ba2+ ions enter the matrix. 140Ba2+ was not accumulated in the mitochondrial matrix space; further, in contrast to liver mitochondria, Ba2+ inhibition was immediate. The Na+-induced Ca2+ release was inhibited by Ba2+ non-competitively, with respect of the extramitochondrial Na+. The double inhibitor titration of the Na+-Ca2+ exchanger with Ba2+ in the presence and absence of extramitochondrial Ca2+ revealed that the exchanger possesses a common binding site for extramitochondrial Ca2+ and Ba2+, presumably the regulatory binding site of the Na+-Ca2+ exchanger, which was described by Hayat and Crompton (Biochem. J. 202 (1982) 509-518). All these observations indicate that Ba2+ acts at the cytoplasmic surface of the inner mitochondrial membrane. The inhibitory properties of Ba2+ on the Na+-dependent Ca2+ release in heart mitochondria are basically different from those found on Na+-independent Ca2+ release in liver mitochondria (Lukács, G.L. and Fonyó, A. (1985) Biochim. Biophys. Acta 809, 160-166).
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