1
|
Zapata Bustos R, Coletta DK, Galons JP, Davidson LB, Langlais PR, Funk JL, Willis WT, Mandarino LJ. Nonequilibrium thermodynamics and mitochondrial protein content predict insulin sensitivity and fuel selection during exercise in human skeletal muscle. Front Physiol 2023; 14:1208186. [PMID: 37485059 PMCID: PMC10361819 DOI: 10.3389/fphys.2023.1208186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2023] [Accepted: 06/16/2023] [Indexed: 07/25/2023] Open
Abstract
Introduction: Many investigators have attempted to define the molecular nature of changes responsible for insulin resistance in muscle, but a molecular approach may not consider the overall physiological context of muscle. Because the energetic state of ATP (ΔGATP) could affect the rate of insulin-stimulated, energy-consuming processes, the present study was undertaken to determine whether the thermodynamic state of skeletal muscle can partially explain insulin sensitivity and fuel selection independently of molecular changes. Methods: 31P-MRS was used with glucose clamps, exercise studies, muscle biopsies and proteomics to measure insulin sensitivity, thermodynamic variables, mitochondrial protein content, and aerobic capacity in 16 volunteers. Results: After showing calibrated 31P-MRS measurements conformed to a linear electrical circuit model of muscle nonequilibrium thermodynamics, we used these measurements in multiple stepwise regression against rates of insulin-stimulated glucose disposal and fuel oxidation. Multiple linear regression analyses showed 53% of the variance in insulin sensitivity was explained by 1) VO2max (p = 0.001) and the 2) slope of the relationship of ΔGATP with the rate of oxidative phosphorylation (p = 0.007). This slope represents conductance in the linear model (functional content of mitochondria). Mitochondrial protein content from proteomics was an independent predictor of fractional fat oxidation during mild exercise (R2 = 0.55, p = 0.001). Conclusion: Higher mitochondrial functional content is related to the ability of skeletal muscle to maintain a greater ΔGATP, which may lead to faster rates of insulin-stimulated processes. Mitochondrial protein content per se can explain fractional fat oxidation during mild exercise.
Collapse
Affiliation(s)
- Rocio Zapata Bustos
- Division of Endocrinology, Department of Medicine, The University of Arizona, Tucson, AZ, United States
- Center for Disparities in Diabetes, Obesity, and Metabolism, University of Arizona, Tucson, AZ, United States
| | - Dawn K. Coletta
- Division of Endocrinology, Department of Medicine, The University of Arizona, Tucson, AZ, United States
- Center for Disparities in Diabetes, Obesity, and Metabolism, University of Arizona, Tucson, AZ, United States
- Department of Physiology, The University of Arizona, Tucson, AZ, United States
| | - Jean-Philippe Galons
- Department of Medical Imaging, The University of Arizona, Tucson, AZ, United States
| | - Lisa B. Davidson
- Division of Endocrinology, Department of Medicine, The University of Arizona, Tucson, AZ, United States
- Center for Disparities in Diabetes, Obesity, and Metabolism, University of Arizona, Tucson, AZ, United States
| | - Paul R. Langlais
- Division of Endocrinology, Department of Medicine, The University of Arizona, Tucson, AZ, United States
- Center for Disparities in Diabetes, Obesity, and Metabolism, University of Arizona, Tucson, AZ, United States
| | - Janet L. Funk
- Division of Endocrinology, Department of Medicine, The University of Arizona, Tucson, AZ, United States
| | - Wayne T. Willis
- Division of Endocrinology, Department of Medicine, The University of Arizona, Tucson, AZ, United States
- Center for Disparities in Diabetes, Obesity, and Metabolism, University of Arizona, Tucson, AZ, United States
| | - Lawrence J. Mandarino
- Division of Endocrinology, Department of Medicine, The University of Arizona, Tucson, AZ, United States
- Center for Disparities in Diabetes, Obesity, and Metabolism, University of Arizona, Tucson, AZ, United States
| |
Collapse
|
2
|
Kim JS, Kim J, Ahn J, Chung S, Han CS. Artificial Action Potential and Ionic Power Device Inspired by Ion Channels and Excitable Cell. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2301037. [PMID: 37026619 DOI: 10.1002/advs.202301037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Indexed: 06/04/2023]
Abstract
In vivo, the membrane potential of the excitable cell working by ion gradients plays a significant role in bioelectricity generation and nervous system operation. Conventional bioinspired power systems generally have adopted ion gradients, but overlook the functions of ion channels and Donnan effect to generate efficient ion flow in the cell. Here, cell-inspired ionic power device implementing the Donnan effect using multi-ions and monovalent ion exchange membranes as artificial ion channels is realized. Different ion-rich electrolytes on either side of the selective membrane generate the ion gradient potentials with high ionic currents and reduce the osmotic imbalance of the membrane. Based on this device, the artificial neuronal signaling is presented by the mechanical switching system of the ion selectivity like mechanosensitive ion channels in a sensory neuron. Compared with reverse electrodialysis, which requires a low concentration, a high-power device with ten times the current and 8.5 times the power density is fabricated. This device activates grown muscle cells by increasing power through serial connection like an electric eel, and shows the possibility of an ion-based artificial nervous system.
Collapse
Affiliation(s)
- Jung-Soo Kim
- Institute of Advanced Machinery Design Technology, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Jongwoon Kim
- Institute of Advanced Machinery Design Technology, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Jinchul Ahn
- School of Mechanical Engineering, College of Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Seok Chung
- School of Mechanical Engineering, College of Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Chang-Soo Han
- Institute of Advanced Machinery Design Technology, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
- School of Mechanical Engineering, College of Engineering, Korea University, 145 Anam-ro, Seongbuk-gu, Seoul, 02841, Republic of Korea
| |
Collapse
|
3
|
Maex R. An Isotonic Model of Neuron Swelling Based on Co-Transport of Salt and Water. MEMBRANES 2023; 13:206. [PMID: 36837709 PMCID: PMC9958824 DOI: 10.3390/membranes13020206] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2022] [Revised: 01/31/2023] [Accepted: 02/06/2023] [Indexed: 06/18/2023]
Abstract
Neurons spend most of their energy building ion gradients across the cell membrane. During energy deprivation the neurons swell, and the concomitant mixing of their ions is commonly assumed to lead toward a Donnan equilibrium, at which the concentration gradients of all permeant ion species have the same Nernst potential. This Donnan equilibrium, however, is not isotonic, as the total concentration of solute will be greater inside than outside the neurons. The present theoretical paper, in contrast, proposes that neurons follow a path along which they swell quasi-isotonically by co-transporting water and ions. The final neuronal volume on the path is taken that at which the concentration of impermeant anions in the shrinking extracellular space equals that inside the swelling neurons. At this final state, which is also a Donnan equilibrium, all permeant ions can mix completely, and their Nernst potentials vanish. This final state is isotonic and electro-neutral, as are all intermediate states along this path. The path is in principle reversible, and maximizes the work of mixing.
Collapse
Affiliation(s)
- Reinoud Maex
- Biocomputation Research Group, School of Physics, Engineering and Computer Science, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK
| |
Collapse
|
4
|
Berndt N, Eckstein J, Wallach I, Nordmeyer S, Kelm M, Kirchner M, Goubergrits L, Schafstedde M, Hennemuth A, Kraus M, Grune T, Mertins P, Kuehne T, Holzhütter HG. CARDIOKIN1: Computational Assessment of Myocardial Metabolic Capability in Healthy Controls and Patients With Valve Diseases. Circulation 2021; 144:1926-1939. [PMID: 34762513 PMCID: PMC8663543 DOI: 10.1161/circulationaha.121.055646] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Supplemental Digital Content is available in the text. Background: Many heart diseases can result in reduced pumping capacity of the heart muscle. A mismatch between ATP demand and ATP production of cardiomyocytes is one of the possible causes. Assessment of the relation between myocardial ATP production (MVATP) and cardiac workload is important for better understanding disease development and choice of nutritional or pharmacologic treatment strategies. Because there is no method for measuring MVATP in vivo, the use of physiology-based metabolic models in conjunction with protein abundance data is an attractive approach. METHOD: We developed a comprehensive kinetic model of cardiac energy metabolism (CARDIOKIN1) that recapitulates numerous experimental findings on cardiac metabolism obtained with isolated cardiomyocytes, perfused animal hearts, and in vivo studies with humans. We used the model to assess the energy status of the left ventricle of healthy participants and patients with aortic stenosis and mitral valve insufficiency. Maximal enzyme activities were individually scaled by means of protein abundances in left ventricle tissue samples. The energy status of the left ventricle was quantified by the ATP consumption at rest (MVATP[rest]), at maximal workload (MVATP[max]), and by the myocardial ATP production reserve, representing the span between MVATP(rest) and MVATP(max). Results: Compared with controls, in both groups of patients, MVATP(rest) was increased and MVATP(max) was decreased, resulting in a decreased myocardial ATP production reserve, although all patients had preserved ejection fraction. The variance of the energetic status was high, ranging from decreased to normal values. In both patient groups, the energetic status was tightly associated with mechanic energy demand. A decrease of MVATP(max) was associated with a decrease of the cardiac output, indicating that cardiac functionality and energetic performance of the ventricle are closely coupled. Conclusions: Our analysis suggests that the ATP-producing capacity of the left ventricle of patients with valvular dysfunction is generally diminished and correlates positively with mechanical energy demand and cardiac output. However, large differences exist in the energetic state of the myocardium even in patients with similar clinical or image-based markers of hypertrophy and pump function. Registration: URL: https://www.clinicaltrials.gov; Unique identifiers: NCT03172338 and NCT04068740.
Collapse
Affiliation(s)
- Nikolaus Berndt
- Institute of Computer-assisted Cardiovascular Medicine, Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Johannes Eckstein
- Institute of Computer-assisted Cardiovascular Medicine, Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; Institute of Biochemistry, Charitá - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Iwona Wallach
- Institute of Computer-assisted Cardiovascular Medicine, Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; Institute of Biochemistry, Charitá - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Sarah Nordmeyer
- Institute of Computer-assisted Cardiovascular Medicine, Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; Department of Congenital Heart Disease - Pediatric Cardiology, Deutsches Herzzentrum Berlin (DHZB), Berlin, Germany
| | - Marcus Kelm
- Institute of Computer-assisted Cardiovascular Medicine, Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; Department of Congenital Heart Disease - Pediatric Cardiology, Deutsches Herzzentrum Berlin (DHZB), Berlin, Germany; Deutsches Zentrum für Herz-Kreislauf-Forschung e. V. (DZHK), Berlin, Germany; Berlin Institute of Health (BIH), Berlin, Germany
| | - Marieluise Kirchner
- Berlin Institute of Health (BIH), Berlin, Germany; Proteomics Platform, Max Delbrück Center for Molecular Medicine (MDC), Berlin, Germany
| | - Leonid Goubergrits
- Institute of Computer-assisted Cardiovascular Medicine, Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; Einstein Center Digital Future, Berlin, Germany
| | - Marie Schafstedde
- Institute of Computer-assisted Cardiovascular Medicine, Charité; Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; Department of Congenital Heart Disease - Pediatric Cardiology, Deutsches Herzzentrum Berlin (DHZB), Berlin, Germany; Berlin Institute of Health (BIH), Berlin, Germany
| | - Anja Hennemuth
- Institute of Computer-assisted Cardiovascular Medicine, Charité Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| | - Milena Kraus
- Digital Health Center, Hasso Plattner Institute, University of Potsdam, Germany
| | - Tilman Grune
- Deutsches Zentrum für Herz-Kreislauf-Forschung e. V. (DZHK), Berlin, Germany; Department of Molecular Toxicology, German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE), Nuthetal, Germany
| | - Philipp Mertins
- Berlin Institute of Health (BIH), Berlin, Germany; Proteomics Platform, Max Delbrück Center for Molecular Medicine (MDC), Berlin, Germany
| | - Titus Kuehne
- Institute of Computer-assisted Cardiovascular Medicine, Charité; Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany; Department of Congenital Heart Disease - Pediatric Cardiology, Deutsches Herzzentrum Berlin (DHZB), Berlin, Germany; Deutsches Zentrum für Herz-Kreislauf-Forschung e. V. (DZHK), Berlin, Germany
| | - Hermann-Georg Holzhütter
- Institute of Biochemistry, Charitá - Universitätsmedizin Berlin, corporate member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany
| |
Collapse
|
5
|
Abstract
There are two types of polyunsaturated fatty acids (i.e. fats that contain multiple carbon-carbon double bonds) - omega-6 and omega-3. They are not interconvertible, and they contribute 'double-bonded carbons' to different depths in bilayer membranes, with different effects on membrane processes. This Commentary emphasises the importance of these fats for biological membrane function and examines their evolution and biochemistry. Omega-6 and omega-3 fatty acids are separately essential in the diet of animals, and they pass up the food chain largely from plants, with 'seeds' being a prevalent source of omega-6, and 'leaves' a prevalent source of omega-3. The dietary balance between these fatty acids has a strong influence on membrane composition. Although this aspect of diet has been little investigated outside of the biomedical field, emerging evidence shows it can alter important physiological capacities of animals (e.g. exercise endurance and adiposity), which has implications for activities such as avian migration and hibernation and torpor, as well as significant implications for human health. This Commentary will focus on the separate effects of omega-3 and omega-6 on membrane properties and will emphasise the importance of the balance between these two fatty acids in determining the function of biological membranes; I hope to convince the reader that fats should be considered first and foremost as the basic unit of biological membranes, and secondarily as a means of energy storage.
Collapse
Affiliation(s)
- A J Hulbert
- School of Earth, Atmospheric and Life Sciences, University of Wollongong, Wollongong 2522, Australia
| |
Collapse
|
6
|
Lecarpentier Y, Kindler V, Krokidis X, Bochaton-Piallat ML, Claes V, Hébert JL, Vallée A, Schussler O. Statistical Mechanics of Non-Muscle Myosin IIA in Human Bone Marrow-Derived Mesenchymal Stromal Cells Seeded in a Collagen Scaffold: A Thermodynamic Near-Equilibrium Linear System Modified by the Tripeptide Arg-Gly-Asp (RGD). Cells 2020; 9:E1510. [PMID: 32575851 PMCID: PMC7349514 DOI: 10.3390/cells9061510] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 06/18/2020] [Accepted: 06/19/2020] [Indexed: 11/25/2022] Open
Abstract
Mesenchymal stromal cells (MSCs) were obtained from human bone marrow and amplified in cultures supplemented with human platelet lysate. Once semi-confluent, cells were seeded in solid collagen scaffolds that were rapidly colonized by the cells generating a 3D cell scaffold. Here, they acquired a myofibroblast phenotype and when exposed to appropriate chemical stimulus, developed tension and cell shortening, similar to those of striated and smooth muscle cells. Myofibroblasts contained a molecular motor-the non-muscle myosin type IIA (NMMIIA) whose crossbridge (CB) kinetics are dramatically slow compared with striated and smooth muscle myosins. Huxley's equations were used to determine the molecular mechanical properties of NMMIIA. Thank to the great number of NMMIIA molecules, we determined the statistical mechanics (SM) of MSCs, using the grand canonical ensemble which made it possible to calculate various thermodynamic entities such as the chemical affinity, statistical entropy, internal energy, thermodynamic flow, thermodynamic force, and entropy production rate. The linear relationship observed between the thermodynamic force and the thermodynamic flow allowed to establish that MSC-laden in collagen scaffolds were in a near-equilibrium stationary state (affinity ≪ RT), MSCs were also seeded in solid collagen scaffolds functionalized with the tripeptide Arg-Gly-Asp (RGD). This induced major changes in NMMIIA SM particularly by increasing the rate of entropy production. In conclusion, collagen scaffolds laden with MSCs can be viewed as a non-muscle contractile bioengineered tissue operating in a near-equilibrium linear regime, whose SM could be substantially modified by the RGD peptide.
Collapse
Affiliation(s)
- Yves Lecarpentier
- Centre de Recherche Clinique, Grand Hôpital de l’Est Francilien, 77104 Meaux, France;
| | - Vincent Kindler
- Department of Specialties in Medicine, Hematology Service, Geneva University Hospital, Faculty of Medicine, 1200 Geneva, Switzerland;
| | - Xénophon Krokidis
- Centre de Recherche Clinique, Grand Hôpital de l’Est Francilien, 77104 Meaux, France;
| | - Marie-Luce Bochaton-Piallat
- Department of Pathology and Immunology, Geneva University Hospital, Faculty of Medicine, 1200 Geneva, Switzerland;
| | - Victor Claes
- Department of Pharmaceutical Sciences, University of Antwerp, 2000 Wilrijk, Belgium;
| | - Jean-Louis Hébert
- Institut de Cardiologie, Hôpital de la Pitié-Salpêtrière, 75013 Paris, France;
| | - Alexandre Vallée
- Diagnosis and Therapeutic Center, Hypertension and Cardiovascular Prevention Unit, Hôtel-Dieu Hospital, AP-HP, Paris-Descartes University, 75004 Paris, France;
| | - Olivier Schussler
- Department of Cardiovascular Surgery, Research Laboratory, Geneva University Hospital, Faculty of Medicine, 1200 Geneva, Switzerland;
- Department of Thoracic surgery, Nouvel Hôpital Civil, Hôpitaux Universitaires de Strasbourg, 67000 Strasbourg, France
| |
Collapse
|
7
|
Dossi G, Squarcina L, Rango M. In Vivo Mitochondrial Function in Idiopathic and Genetic Parkinson's Disease. Metabolites 2019; 10:metabo10010019. [PMID: 31905632 PMCID: PMC7023121 DOI: 10.3390/metabo10010019] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 12/20/2019] [Accepted: 12/26/2019] [Indexed: 01/26/2023] Open
Abstract
Parkinson’s disease (PD) is associated with brain mitochondrial dysfunction. High-energy phosphates (HEPs), which rely on mitochondrial functioning, may be considered potential biomarkers for PD. Phosphorus magnetic resonance spectroscopy (31P-MRS) is a suitable tool to explore in vivo cerebral energetics. We considered 10 31P-MRS studies in order to highlight the main findings about brain energetic compounds in patients affected by idiopathic PD and genetic PD. The studies investigated several brain areas such as frontal lobes, occipital lobes, temporoparietal cortex, visual cortex, midbrain, and basal ganglia. Resting-state studies reported contrasting results showing decreased as well as normal or increased HEPs levels in PD patients. Functional studies revealed abnormal PCr + βATP levels in PD subjects during the recovery phase and abnormal values at rest, during activation and recovery in one PD subject with PINK1 gene mutation suggesting that mitochondrial machinery is more impaired in PD patients with PINK1 gene mutation. PD is characterized by energetics impairment both in idiopathic PD as well as in genetic PD, suggesting that mitochondrial dysfunction underlies the disease. Studies are still sparse and sometimes contrasting, maybe due to different methodological approaches. Further studies are needed to better assess the role of mitochondria in the PD development.
Collapse
|
8
|
Veech RL, King MT, Pawlosky R, Bradshaw PC, Curtis W. Relationship between inorganic ion distribution, resting membrane potential, and the Δ G' of ATP hydrolysis: a new paradigm. FASEB J 2019; 33:13126-13130. [PMID: 31690124 DOI: 10.1096/fj.201901942r] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Cell membrane potential and inorganic ion distributions are currently viewed from a kinetic electric paradigm, which ignores thermodynamics. The resting membrane potential is viewed as a diffusion potential. The 9 major inorganic ions found in blood plasma (Ca2+, Na+, Mg2+, K+, H+, Cl-, HCO3-, H2PO4-, and HPO42-) are distributed unequally across the plasma membrane. This unequal distribution requires the energy of ATP hydrolysis through the action of the Na+-K+ ATPase. The cell resting membrane potential in each of 3 different tissues with widely different resting membrane potentials has been shown to be equal to the Nernst equilibrium potential of the most permeant inorganic ion. The energy of the measured distribution of the 9 major inorganic ions between extra- and intracellular phases was essentially equal to the independently measured energy of ATP hydrolysis, showing that the distribution of these 9 major ions was in near-equilibrium with the ΔG' of ATP. Therefore, thermodynamics does appear to play an essential role in the determination of the cell resting membrane potential and the inorganic ion distribution across the plasma membrane.-Veech, R. L., King, M. T., Pawlosky, R., Bradshaw, P. C., Curtis, W. Relationship between inorganic ion distribution, resting membrane potential, and the ΔG' of ATP hydrolysis: a new paradigm.
Collapse
Affiliation(s)
- Richard L Veech
- Laboratory of Metabolic Control, National Institute on Alcohol Abuse and Alcoholism (NIAAA), National Institutes of Health (NIH), Rockville, Maryland, USA
| | - M Todd King
- Laboratory of Metabolic Control, National Institute on Alcohol Abuse and Alcoholism (NIAAA), National Institutes of Health (NIH), Rockville, Maryland, USA
| | - Robert Pawlosky
- Laboratory of Metabolic Control, National Institute on Alcohol Abuse and Alcoholism (NIAAA), National Institutes of Health (NIH), Rockville, Maryland, USA
| | - Patrick C Bradshaw
- Department of Biomedical Sciences, East Tennessee State University College of Medicine, Johnson City, Tennessee, USA
| | - William Curtis
- Department of Biomedical Sciences, East Tennessee State University College of Medicine, Johnson City, Tennessee, USA
| |
Collapse
|
9
|
Fasting as a Therapy in Neurological Disease. Nutrients 2019; 11:nu11102501. [PMID: 31627405 PMCID: PMC6836141 DOI: 10.3390/nu11102501] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2019] [Revised: 10/12/2019] [Accepted: 10/15/2019] [Indexed: 12/16/2022] Open
Abstract
Fasting is deeply entrenched in evolution, yet its potential applications to today’s most common, disabling neurological diseases remain relatively unexplored. Fasting induces an altered metabolic state that optimizes neuron bioenergetics, plasticity, and resilience in a way that may counteract a broad array of neurological disorders. In both animals and humans, fasting prevents and treats the metabolic syndrome, a major risk factor for many neurological diseases. In animals, fasting probably prevents the formation of tumors, possibly treats established tumors, and improves tumor responses to chemotherapy. In human cancers, including cancers that involve the brain, fasting ameliorates chemotherapy-related adverse effects and may protect normal cells from chemotherapy. Fasting improves cognition, stalls age-related cognitive decline, usually slows neurodegeneration, reduces brain damage and enhances functional recovery after stroke, and mitigates the pathological and clinical features of epilepsy and multiple sclerosis in animal models. Primarily due to a lack of research, the evidence supporting fasting as a treatment in human neurological disorders, including neurodegeneration, stroke, epilepsy, and multiple sclerosis, is indirect or non-existent. Given the strength of the animal evidence, many exciting discoveries may lie ahead, awaiting future investigations into the viability of fasting as a therapy in neurological disease.
Collapse
|
10
|
D'Rozario AL, Bartlett DJ, Wong KKH, Sach T, Yang Q, Grunstein RR, Rae CD. Brain bioenergetics during resting wakefulness are related to neurobehavioral deficits in severe obstructive sleep apnea: a 31P magnetic resonance spectroscopy study. Sleep 2019; 41:5026697. [PMID: 29868772 DOI: 10.1093/sleep/zsy117] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Indexed: 11/15/2022] Open
Abstract
Study Objectives Obstructive sleep apnea (OSA) is a well-established cause of impaired daytime functioning. However, there is a complex inter-individual variability in neurobehavioral performance in OSA patients. We previously reported compromised brain bioenergetics during apneic sleep in severe OSA. In this study, we investigate whether brain bioenergetics during resting wakefulness are related to neurobehavioral performance. Methods Patients attended the sleep laboratory in the evening and were kept awake over-night. Repeated testing on the 10-minute psychomotor vigilance task (PVT, at 9 pm, 11 pm, 1 am, 3 am, 5 am) and 30-minute AusEd driving simulator task (9 pm and 5 am) was performed. Brain bioenergetics (inorganic phosphate/adenosine triphosphate ratio, Pi/ATP) were measured in the temporal lobe during resting wakefulness at 7 am in a 1.5T MRI scanner using phosphorus magnetic resonance spectroscopy (31P MRS). Results Fifteen males with severe OSA (age 47.7 ± 10.4 years, body mass index [BMI] 34 ± 6.6 kg/m2, apnea hypopnea index [AHI] 79.7 ± 21.8/hour) were investigated. A higher Pi/ATP ratio in the brain (lower phosphorylation potential) was correlated with worse PVT and driving simulator performance across the testing period (PVT lapses: r = 0.632, r2 = 0.399, p = 0.012; and AusEd braking reaction time: r = 0.609, p = 0.016). In contrast, the conventional AHI measure of disease severity was not significantly correlated with performance (PVT lapses: r = -0.084, p = 0.8; and AusEd braking reaction time: r = -0.326, p = 0.2). Conclusions Lower phosphorylation potential was associated with worse performance. Compromised brain bioenergetics may in part underlie the neurobehavioral deficits in untreated OSA. We speculate that better brain bioenergetics may explain why some OSA patients are relatively asymptomatic compared with others.
Collapse
Affiliation(s)
- Angela L D'Rozario
- CIRUS, Woolcock Institute of Medical Research, University of Sydney and Sydney Health Partners, Sydney, New South Wales, Australia
- School of Psychology, Faculty of Science, Brain and Mind Centre and Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia
- Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
| | - Delwyn J Bartlett
- CIRUS, Woolcock Institute of Medical Research, University of Sydney and Sydney Health Partners, Sydney, New South Wales, Australia
- Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
| | - Keith K H Wong
- CIRUS, Woolcock Institute of Medical Research, University of Sydney and Sydney Health Partners, Sydney, New South Wales, Australia
- Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
- Respiratory and Sleep Disorders Department, Royal Prince Alfred Hospital, Camperdown, New South Wales, Australia
| | - Toos Sach
- Rayscan Imaging, Goulburn St, Liverpool, New South Wales, Australia
| | - Qiao Yang
- CIRUS, Woolcock Institute of Medical Research, University of Sydney and Sydney Health Partners, Sydney, New South Wales, Australia
| | - Ronald R Grunstein
- CIRUS, Woolcock Institute of Medical Research, University of Sydney and Sydney Health Partners, Sydney, New South Wales, Australia
- Sydney Medical School, University of Sydney, Sydney, New South Wales, Australia
- Respiratory and Sleep Disorders Department, Royal Prince Alfred Hospital, Camperdown, New South Wales, Australia
| | - Caroline D Rae
- Neuroscience Research Australia, Sydney, New South Wales, Australia
- School of Medical Sciences, University of New South Wales, Sydney, New South Wales, Australia
| |
Collapse
|
11
|
Veech RL, Todd King M, Pawlosky R, Kashiwaya Y, Bradshaw PC, Curtis W. The "great" controlling nucleotide coenzymes. IUBMB Life 2019; 71:565-579. [PMID: 30624851 PMCID: PMC6850382 DOI: 10.1002/iub.1997] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 12/04/2018] [Accepted: 12/05/2018] [Indexed: 12/11/2022]
Abstract
Nucleotide coenzymes dot the map of metabolic pathways providing energy to drive the reactions of the pathway and play an important role in regulating and controlling energy metabolism through their shared potential energy, which is widely unobserved due to the paradox that the energy in the coenzyme pools cannot be determined from the concentration of the coenzyme couples. The potential energy of the nucleotide couples in the mitochondria or the cytoplasm is expressed in the enzyme reactions in which they take part. The energy in these couples, [NAD+]/[NADH], [NADP+]/[NADPH], [acetyl CoA]/[CoA], and [ATP]/[ADP]x[Pi], regulates energy metabolism. The energy contained in the couples can be altered by suppling energy equivalents in the form of ketones, such as, D-β-hydroxybutyrate to overcome insulin resistance, to restore antioxidants capacity, to form potential treatments for Alzheimer's and Parkinson's diseases, to enhance life span, and to increase physiological performance. © 2019 IUBMB Life, 71(5):565-579, 2019.
Collapse
Affiliation(s)
- Richard L Veech
- Laboratory of Metabolic Control, NIAAA, NIH, Rockville, MD, 20852, USA
| | - Michael Todd King
- Laboratory of Metabolic Control, NIAAA, NIH, Rockville, MD, 20852, USA
| | - Robert Pawlosky
- Laboratory of Metabolic Control, NIAAA, NIH, Rockville, MD, 20852, USA
| | | | - Patrick C Bradshaw
- Department of Biomedical Sciences, East Tennessee State University College of Medicine, Johnson City, TN, USA
| | - William Curtis
- Department of Biomedical Sciences, East Tennessee State University College of Medicine, Johnson City, TN, USA
| |
Collapse
|
12
|
Shapshak P. Astrovirology, Astrobiology, Artificial Intelligence: Extra-Solar System Investigations. GLOBAL VIROLOGY III: VIROLOGY IN THE 21ST CENTURY 2019. [PMCID: PMC7120930 DOI: 10.1007/978-3-030-29022-1_20] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
This chapter attempts to encompass and tackle a large problem in Astrovirology and Astrobiology. There is a huge anthropomorphic prejudice that although life is unlikely, the just-right Goldilocks terrestrial conditions mean that the just-right balance of minerals and basic small molecules inevitably result in life as we know it throughout our solar system, galaxy, and the rest of the universe. Moreover, when such conditions on planets such as ours may not be quite right for the origin of life, it is popularly opined that asteroids and comets magically produce life or at the very least, the important, if not crucial components of terrestrial life so that life then blooms, when their fragments cruise the solar system, stars, and galaxies, and plummet onto appropriately bedecked planets and moons. It is no longer extraordinary to detect extraterrestrial solar systems. Moreover, since extra-solar system space exploration has commenced, this provides the problem of detecting life with enhanced achievability. Small organisms, which replicate outside of a living cell or host, would not be catalogued as viruses. How about viruses that cohabit with life? On the Earth, viruses are a major, if underestimated, condition of life – will that be the case elsewhere? Detection of extra-solar system viruses, if they exist, requires finding life, since viruses necessitate life to replicate. (It should be noted, though, that viruses could be detected through various types of portable ultra-microscopes, including Electron Microscopes (EM) (scanning and transmission) as well as Atomic Force Microscopes (AFM).) However, extra-solar system detection of life does not oblige that viruses exist ubiquitously. Viruses are important potential components of biospheres because of their multiple interactions and influence on evolution, although viruses are small and obligatory parasitic. In addition, nanotechnology – living or replicating nano-synthetic machine organisms might also be present out there, and require consideration as well. An imposing caveat is that, if found, could some extraterrestrial viruses and synthetic nanotechnological microorganisms infect humans? Possibly, intelligence and cognition may at times be contemporaneous with life. Concomitantly, life and viruses that may be detected, could well be impacted upon by intelligences existing on such exoplanets (and vice versa). Coming to an understanding of the plurality of extraterrestrial intelligence is an optimal objective, in order to avoid causing harm on exoplanets, as well as avoiding conflict and possible human devastation. This is especially the case if we encounter greatly advanced galactic-level civilizations, compared to terrestrial civilizations. Their machine and bionic technologies on the Dyson engineering civilization scale may be prominently superior to ours; their biological expertise may be similarly critically radical. For example, they may use viruses for purposes for which we are barely aware, and which could be utterly deadly for humans. A series of steps is being taken in space exploration. Scientists hypothesize and claim that types of life may be near the Earth, in the solar system, and outside the solar system, similar to ours in the sense that only such conditions, Goldilocks conditions, are key sine qua non requirements, based on our terrestrial chemistry and biochemistry. If detected within the solar system, will life or its remnants resemble terrestrial life? Outside the solar system a similar chauvinism exists, although the likelihood for life, in any event, remains probably low, according to more cautious approaches to the problem. The study of our solar system includes planets, asteroids, comets, and other planetesimals that have been in overall contiguity during several billion years; anthropomorphisms claims life consequently has been developing along terrestrial-type mechanisms. However, a non-anthropomorphic view would surmise, probably not, especially for extra-solar system locales. The prime warning and admonition in all these deliberations is the contamination and damage, which current and past practice and procedures has caused and continues, due to insufficient biocontainment concepts and technology to date. Advances in the development of robotics, artificial intelligence (AI), and high capacity ultrafast quantum computers (QC) greatly enhance the sophisticated control and logical development of extra-solar system studies. Consequently, future long-range manned space exploration seems unwarranted. Clearly, reduced dangers to human health and safety, will result from the use of intelligent machine-based investigations and besides, with increased cost-effectiveness. Space exploration comes at great cost to humanity as a whole and utilizes global resources. Consequently, appropriate organizational measures and planning/cooperation need to be in place. Moreover, the bottom line is that despite all the slogans and claims, there have been next to no financial benefits to our planet as a whole. Such financial and heedless difficulties need to be addressed, the sooner the better. In addition, prior to exposure to exoplanetary life, deep understanding of the problems of infectious diseases and immune dysfunction risks are needed. In addition, global efforts should avoid serendipity and stochasticity as this work should be directed with long-term organization, commitment, scientific, and technological methodology. This chapter briefly reviews such questions assuming a new paradigm for oversight of extrasolar system viral investigations including intelligence and life. Finances are included as an essential adjunct.
Collapse
|
13
|
Comparative Statistical Mechanics of Muscle and Non-Muscle Contractile Systems: Stationary States of Near-Equilibrium Systems in A Linear Regime. ENTROPY 2017. [DOI: 10.3390/e19100558] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
14
|
Willis WT, Jackman MR, Messer JI, Kuzmiak-Glancy S, Glancy B. A Simple Hydraulic Analog Model of Oxidative Phosphorylation. Med Sci Sports Exerc 2017; 48:990-1000. [PMID: 26807634 DOI: 10.1249/mss.0000000000000884] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Mitochondrial oxidative phosphorylation is the primary source of cellular energy transduction in mammals. This energy conversion involves dozens of enzymatic reactions, energetic intermediates, and the dynamic interactions among them. With the goal of providing greater insight into the complex thermodynamics and kinetics ("thermokinetics") of mitochondrial energy transduction, a simple hydraulic analog model of oxidative phosphorylation is presented. In the hydraulic model, water tanks represent the forward and back "pressures" exerted by thermodynamic driving forces: the matrix redox potential (ΔGredox), the electrochemical potential for protons across the mitochondrial inner membrane (ΔGH), and the free energy of adenosine 5'-triphosphate (ATP) (ΔGATP). Net water flow proceeds from tanks with higher water pressure to tanks with lower pressure through "enzyme pipes" whose diameters represent the conductances (effective activities) of the proteins that catalyze the energy transfer. These enzyme pipes include the reactions of dehydrogenase enzymes, the electron transport chain (ETC), and the combined action of ATP synthase plus the ATP-adenosine 5'-diphosphate exchanger that spans the inner membrane. In addition, reactive oxygen species production is included in the model as a leak that is driven out of the ETC pipe by high pressure (high ΔGredox) and a proton leak dependent on the ΔGH for both its driving force and the conductance of the leak pathway. Model water pressures and flows are shown to simulate thermodynamic forces and metabolic fluxes that have been experimentally observed in mammalian skeletal muscle in response to acute exercise, chronic endurance training, and reduced substrate availability, as well as account for the thermokinetic behavior of mitochondria from fast- and slow-twitch skeletal muscle and the metabolic capacitance of the creatine kinase reaction.
Collapse
Affiliation(s)
- Wayne T Willis
- 1Center for Metabolic and Vascular Biology, Arizona State University at Mayo Clinic, Scottsdale, AZ; 2Division of Endocrinology, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO; 3Exercise Science Department, Mesa Community College, Mesa, AZ; 4Department of Biomedical Engineering, The George Washington University, Washington, DC; and 5Laboratory of Cardiac Energetics, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD
| | | | | | | | | |
Collapse
|
15
|
Lecarpentier Y, Claes V, Hébert JL, Krokidis X, Blanc FX, Michel F, Timbely O. Statistical Mechanics of the Human Placenta: A Stationary State of a Near-Equilibrium System in a Linear Regime. PLoS One 2015; 10:e0142471. [PMID: 26569482 PMCID: PMC4646433 DOI: 10.1371/journal.pone.0142471] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 10/22/2015] [Indexed: 11/19/2022] Open
Abstract
All near-equilibrium systems under linear regime evolve to stationary states in which there is constant entropy production rate. In an open chemical system that exchanges matter and energy with the exterior, we can identify both the energy and entropy flows associated with the exchange of matter and energy. This can be achieved by applying statistical mechanics (SM), which links the microscopic properties of a system to its bulk properties. In the case of contractile tissues such as human placenta, Huxley's equations offer a phenomenological formalism for applying SM. SM was investigated in human placental stem villi (PSV) (n = 40). PSV were stimulated by means of KCl exposure (n = 20) and tetanic electrical stimulation (n = 20). This made it possible to determine statistical entropy (S), internal energy (E), affinity (A), thermodynamic force (A / T) (T: temperature), thermodynamic flow (v) and entropy production rate (A / T x v). We found that PSV operated near equilibrium, i.e., A ≺≺ 2500 J/mol and in a stationary linear regime, i.e., (A / T) varied linearly with v. As v was dramatically low, entropy production rate which quantified irreversibility of chemical processes appeared to be the lowest ever observed in any contractile system.
Collapse
Affiliation(s)
- Yves Lecarpentier
- Centre de Recherche Clinique, Centre Hospitalier Régional de Meaux, Meaux, France
| | - Victor Claes
- Department of Pharmaceutical Sciences, University of Antwerp, Wilrijk, Belgium
| | - Jean-Louis Hébert
- Institut de Cardiologie, Hôpital de la Pitié-Salpêtrière, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Xénophon Krokidis
- Centre de Recherche Clinique, Centre Hospitalier Régional de Meaux, Meaux, France
| | | | - Francine Michel
- Service de Gynécologie-Obstétrique, Centre Hospitalier Régional de Meaux, Meaux, France
| | - Oumar Timbely
- Service de Gynécologie-Obstétrique, Centre Hospitalier Régional de Meaux, Meaux, France
| |
Collapse
|
16
|
Plante DT, Trksak GH, Jensen JE, Penetar DM, Ravichandran C, Riedner BA, Tartarini WL, Dorsey CM, Renshaw PF, Lukas SE, Harper DG. Gray matter-specific changes in brain bioenergetics after acute sleep deprivation: a 31P magnetic resonance spectroscopy study at 4 Tesla. Sleep 2014; 37:1919-27. [PMID: 25325507 DOI: 10.5665/sleep.4242] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Accepted: 07/03/2014] [Indexed: 01/21/2023] Open
Abstract
STUDY OBJECTIVES A principal function of sleep may be restoration of brain energy metabolism caused by the energetic demands of wakefulness. Because energetic demands in the brain are greater in gray than white matter, this study used linear mixed-effects models to examine tissue-type specific changes in high-energy phosphates derived using 31P magnetic resonance spectroscopy (MRS) after sleep deprivation and recovery sleep. DESIGN Experimental laboratory study. SETTING Outpatient neuroimaging center at a private psychiatric hospital. PARTICIPANTS A total of 32 MRS scans performed in eight healthy individuals (mean age 35 y; range 23-51 y). INTERVENTIONS Phosphocreatine (PCr) and β-nucleoside triphosphate (NTP) were measured using 31P MRS three dimensional-chemical shift imaging at high field (4 Tesla) after a baseline night of sleep, acute sleep deprivation (SD), and 2 nights of recovery sleep. Novel linear mixed-effects models were constructed using spectral and tissue segmentation data to examine changes in bioenergetics in gray and white matter. MEASUREMENTS AND RESULTS PCr increased in gray matter after 2 nights of recovery sleep relative to SD with no significant changes in white matter. Exploratory analyses also demonstrated that increases in PCr were associated with increases in electroencephalographic slow wave activity during recovery sleep. No significant changes in β-NTP were observed. CONCLUSIONS These results demonstrate that sleep deprivation and subsequent recovery-induced changes in high-energy phosphates primarily occur in gray matter, and increases in PCr after recovery sleep may be related to sleep homeostasis.
Collapse
Affiliation(s)
- David T Plante
- Department of Psychiatry, University of Wisconsin School of Medicine and Public Health, Madison, WI
| | - George H Trksak
- Behavioral Psychopharmacology Research Lab, McLean Hospital, Belmont, MA: Brain Imaging Center, McLean Hospital, Belmont, MA: Sleep Research Laboratory, McLean Hospital, Belmont, MA: Harvard Medical School, Boston, MA
| | - J Eric Jensen
- Brain Imaging Center, McLean Hospital, Belmont, MA: Harvard Medical School, Boston, MA
| | - David M Penetar
- Behavioral Psychopharmacology Research Lab, McLean Hospital, Belmont, MA: Brain Imaging Center, McLean Hospital, Belmont, MA: Sleep Research Laboratory, McLean Hospital, Belmont, MA: Harvard Medical School, Boston, MA
| | - Caitlin Ravichandran
- Harvard Medical School, Boston, MA: Laboratory for Psychiatric Biostatistics, McLean Hospital, Belmont, MA
| | - Brady A Riedner
- Department of Psychiatry, University of Wisconsin School of Medicine and Public Health, Madison, WI
| | | | - Cynthia M Dorsey
- Brain Imaging Center, McLean Hospital, Belmont, MA: Sleep Research Laboratory, McLean Hospital, Belmont, MA: Harvard Medical School, Boston, MA
| | - Perry F Renshaw
- The Brain Institute, University of Utah School of Medicine, Salt Lake City, UT
| | - Scott E Lukas
- Behavioral Psychopharmacology Research Lab, McLean Hospital, Belmont, MA: Brain Imaging Center, McLean Hospital, Belmont, MA: Sleep Research Laboratory, McLean Hospital, Belmont, MA: Harvard Medical School, Boston, MA
| | - David G Harper
- Harvard Medical School, Boston, MA: Geriatric Psychiatry Program, McLean Hospital, Belmont, MA
| |
Collapse
|
17
|
Palacios-Prado N, Chapuis S, Panjkovich A, Fregeac J, Nagy JI, Bukauskas FF. Molecular determinants of magnesium-dependent synaptic plasticity at electrical synapses formed by connexin36. Nat Commun 2014; 5:4667. [PMID: 25135336 PMCID: PMC4142521 DOI: 10.1038/ncomms5667] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Accepted: 07/11/2014] [Indexed: 01/28/2023] Open
Abstract
Neuronal gap junction (GJ) channels composed of connexin36 (Cx36) play an important role in neuronal synchronization and network dynamics. Here we show that Cx36-containing electrical synapses between inhibitory neurons of the thalamic reticular nucleus are bidirectionally modulated by changes in intracellular free magnesium concentration ([Mg(2+)]i). Chimeragenesis demonstrates that the first extracellular loop of Cx36 contains a Mg(2+)-sensitive domain, and site-directed mutagenesis shows that the pore-lining residue D47 is critical in determining high Mg(2+)-sensitivity. Single-channel analysis of Mg(2+)-sensitive chimeras and mutants reveals that [Mg(2+)]i controls the strength of electrical coupling mostly via gating mechanisms. In addition, asymmetric transjunctional [Mg(2+)]i induces strong instantaneous rectification, providing a novel mechanism for electrical rectification in homotypic Cx36 GJs. We suggest that Mg(2+)-dependent synaptic plasticity of Cx36-containing electrical synapses could underlie neuronal circuit reconfiguration via changes in brain energy metabolism that affects neuronal levels of intracellular ATP and [Mg(2+)]i.
Collapse
Affiliation(s)
- Nicolás Palacios-Prado
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, NY 10461, USA
- Grass Laboratory, Marine Biological Laboratory, Woods Hole, MA 02543, USA
| | - Sandrine Chapuis
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, NY 10461, USA
| | - Alejandro Panjkovich
- European Molecular Biology Laboratory, Hamburg Outstation, 22603 Hamburg, Germany
| | - Julien Fregeac
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, NY 10461, USA
| | - James I. Nagy
- Department of Physiology, University of Manitoba, Winnipeg, Manitoba R3E 0J9, Canada
| | - Feliksas F. Bukauskas
- Dominick P. Purpura Department of Neuroscience, Albert Einstein College of Medicine, NY 10461, USA
| |
Collapse
|
18
|
Pacini N, Borziani F. Cancer stem cell theory and the warburg effect, two sides of the same coin? Int J Mol Sci 2014; 15:8893-930. [PMID: 24857919 PMCID: PMC4057766 DOI: 10.3390/ijms15058893] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2014] [Revised: 04/28/2014] [Accepted: 05/12/2014] [Indexed: 12/12/2022] Open
Abstract
Over the last 100 years, many studies have been performed to determine the biochemical and histopathological phenomena that mark the origin of neoplasms. At the end of the last century, the leading paradigm, which is currently well rooted, considered the origin of neoplasms to be a set of genetic and/or epigenetic mutations, stochastic and independent in a single cell, or rather, a stochastic monoclonal pattern. However, in the last 20 years, two important areas of research have underlined numerous limitations and incongruities of this pattern, the hypothesis of the so-called cancer stem cell theory and a revaluation of several alterations in metabolic networks that are typical of the neoplastic cell, the so-called Warburg effect. Even if this specific “metabolic sign” has been known for more than 85 years, only in the last few years has it been given more attention; therefore, the so-called Warburg hypothesis has been used in multiple and independent surveys. Based on an accurate analysis of a series of considerations and of biophysical thermodynamic events in the literature, we will demonstrate a homogeneous pattern of the cancer stem cell theory, of the Warburg hypothesis and of the stochastic monoclonal pattern; this pattern could contribute considerably as the first basis of the development of a new uniform theory on the origin of neoplasms. Thus, a new possible epistemological paradigm is represented; this paradigm considers the Warburg effect as a specific “metabolic sign” reflecting the stem origin of the neoplastic cell, where, in this specific metabolic order, an essential reason for the genetic instability that is intrinsic to the neoplastic cell is defined.
Collapse
Affiliation(s)
- Nicola Pacini
- Laboratorio Privato di Biochimica F. Pacini, via trabocchetto 10, 89126 Reggio Calabria, Italy.
| | - Fabio Borziani
- Laboratorio Privato di Biochimica F. Pacini, via trabocchetto 10, 89126 Reggio Calabria, Italy.
| |
Collapse
|
19
|
Anodal transcranial direct current stimulation increases brain intracellular pH and modulates bioenergetics. Int J Neuropsychopharmacol 2013; 16:1695-706. [PMID: 23473040 DOI: 10.1017/s1461145713000084] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Transcranial direct current stimulation is an emerging treatment for brain disorders but its mode of action is not well understood. We applied 10 min 1 mA anodal transcranial direct current stimulation (tDCS) inside the bore of a 3 T MRI scanner to the left dorsolateral prefrontal cortex of 13 healthy volunteers (aged 19-28 yr) in a blinded, sham-controlled, cross-over design. Brain bioenergetics were measured from the left temporo-frontal region using 31P magnetic resonance spectroscopy before, during and for 20 min following tDCS. Brain pH rose during tDCS and remained elevated afterwards. Phosphomonoesters were significantly decreased while inorganic phosphate (Pi) also fell. Partial-least squares discriminant analysis of the data revealed two significantly different subject groups: one where phosphocreatine (PCr), ATP and Pi fell along with a larger increase in pH and one where PCr and ATP increased along with a smaller increase in pH and a slower and more sustained decrease in Pi. Group membership was predicted by baseline pH and ATP. We interpreted the effects of tDCS as driving two biochemical processes: cellular consumption of ATP causing hydrolysis of PCr via the creatine kinase reaction driving the increase in pH; synthesis of ATP and PCr by mitochondria with concomitant drop in Pi and phosphomonoester levels.
Collapse
|
20
|
Niwano S, Hirasawa S, Niwano H, Sasaki S, Masuda R, Sato K, Masuda T, Izumi T. Cardioprotective Effects of Sarcolemmal and Mitochondrial K-ATP Channel Openers in an Experimental Model of Autoimmune Myocarditis. Int Heart J 2012; 53:139-45. [DOI: 10.1536/ihj.53.139] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- Shinichi Niwano
- Department of Cardio-Angiology, Kitasato University School of Medicine
| | - Shoji Hirasawa
- Department of Cardio-Angiology, Kitasato University School of Medicine
| | - Hiroe Niwano
- Department of Cardio-Angiology, Kitasato University School of Medicine
| | - Sae Sasaki
- Department of Cardio-Angiology, Kitasato University School of Medicine
| | | | - Kiyotaka Sato
- Department of Neurology, Kitasato University School of Medicine
| | - Takashi Masuda
- Department of Cardio-Angiology, Kitasato University School of Medicine
| | - Tohru Izumi
- Department of Cardio-Angiology, Kitasato University School of Medicine
| |
Collapse
|
21
|
Comparative statistical mechanics of myosin molecular motors in rat heart, diaphragm and tracheal smooth muscle. C R Biol 2011; 334:725-36. [PMID: 21943522 DOI: 10.1016/j.crvi.2011.08.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2010] [Revised: 07/11/2011] [Accepted: 08/02/2011] [Indexed: 11/20/2022]
Abstract
PURPOSE Statistical mechanics establishes a link between microscopic properties of matter and its bulk properties. A. Huxley's equations (1957) [1] provide the necessary phenomenological formalism to use statistical mechanics. METHODS We compared statistical mechanics in rat diaphragm in tetanus (tet; n=10) and twitch (tw; n=12) modes, in heart in twitch mode (n=20), and in tracheal smooth muscle in tetanus mode (TSM; n=10). This powerful tool makes it possible to determine: (i) statistical entropy (S) which is related to the dispersal of energy and represents a measure of the degree of disorder in muscular system; (ii) thermodynamic force A/T (chemical affinity A and temperature T); (iii) thermodynamic flow (υ); (iv) entropy production rate (A/T×υ), which quantifies irreversible chemical processes generated by myosin crossbridge (CB) molecular motors. RESULTS All muscles studied operated near equilibrium, i.e., A<<2500J/mol and in a stationary linear regime, i.e., A/T varied linearly with υ. The heart operated farther from equilibrium than both diaphragm (tet and tw) and TSM, as attested by its high entropy production rate. S was of the same order of magnitude in heart and TSM but lower in diaphragm (tet and tw). CONCLUSION CB kinetics derived from A. Huxley's equations conferred a characteristic profile in terms of statistical mechanics on each muscle type. All studied muscles differed in terms of statistical entropy, chemical affinity, and entropy production rate. Stimulation mode (tet and tw) modulated CB kinetics and statistical mechanics. All muscle types operated near equilibrium and in a stationary linear regime.
Collapse
|
22
|
Bergman C, Kashiwaya Y, Veech RL. The effect of pH and free Mg2+ on ATP linked enzymes and the calculation of Gibbs free energy of ATP hydrolysis. J Phys Chem B 2010; 114:16137-46. [PMID: 20866109 DOI: 10.1021/jp105723r] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The apparent equilibrium constants, K′, of biochemical reactions containing substrates which bind [Mg2+] unequally can be significantly altered by changes in free intracellular [Mg2+]. Intracellular free [Mg2+] can be estimated by measurements of [citrate]/[isocitrate], a ratio known to vary with tissue free [Mg2+]. The combined equilibrium constant for glyceraldehyde-3-phosphate dehydrogenase, phosphoglycerate kinase, and triose phosphate isomerase for the three reactions (K(GG-TPI)′) was corrected using new binding constants for dihydroxyacetone-phosphate and 3-phosphoglycerate. The result of this calculation is demonstrated in the calculation of the free energy of ATP hydrolysis. In addition, the dependence of the equilibrium constant for the glutamine synthetase reaction on pH and free [Mg2+] was demonstrated. Furthermore, a theory linking the ΔG′ value of mitochondrial complex I−II and the cytosolic ΔG′ value of ATP hydrolysis is discussed with evidence from previous publications.
Collapse
Affiliation(s)
- Christian Bergman
- Laboratory of Metabolic Control, NIAAA, NIH, DHHS, 5625 Fishers Lane, Bethesda, Maryland 20892, USA
| | | | | |
Collapse
|
23
|
Sloots KL, Dobson GP. Normokalemic adenosine–lidocaine cardioplegia: Importance of maintaining a polarized myocardium for optimal arrest and reanimation. J Thorac Cardiovasc Surg 2010; 139:1576-86. [DOI: 10.1016/j.jtcvs.2009.10.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Revised: 09/18/2009] [Accepted: 10/04/2009] [Indexed: 10/19/2022]
|
24
|
Lecarpentier Y, Krokidis X, Martin P, Pineau T, Hébert JL, Quillard J, Cortes-Morichetti M, Coirault C. Increased entropy production in diaphragm muscle of PPARα knockout mice. J Theor Biol 2008; 250:92-102. [DOI: 10.1016/j.jtbi.2007.09.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2007] [Revised: 07/13/2007] [Accepted: 09/01/2007] [Indexed: 11/30/2022]
|
25
|
Veech RL. The determination of the redox states and phosphorylation potential in living tissues and their relationship to metabolic control of disease phenotypes. BIOCHEMISTRY AND MOLECULAR BIOLOGY EDUCATION : A BIMONTHLY PUBLICATION OF THE INTERNATIONAL UNION OF BIOCHEMISTRY AND MOLECULAR BIOLOGY 2006; 34:168-79. [PMID: 21638666 DOI: 10.1002/bmb.2006.49403403168] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
This paper reviews the development in the 1950s of methods to determine the redox states of the free [NAD(+) ]/[NADH] in cytoplasm of yeast by Helmut Holzer and Feodore Lynen and in rat liver by Theodore Bucher and Martin Klingenberg. This work was extended in the 1960s in the laboratory of Hans Krebs, where the use of basic thermodynamic and kinetic principles allowed the extension of this approach to the determination of the free mitochondrial [NAD(+) ]/NADH] in mitochondria and the redox state of the free NADP system in cytoplasm and mitochondria. This work also outlined the linkage between the redox states in the various couples to the phosphorylation state or the free [ATP]/[ADP][P(i) ] ratio, the central energy parameter of living cells. This work has since been extended to include other energy-linked systems including the gradients of inorganic ions between extra and intracellular phases of the cell and the redox state of the co-enzyme Q couple of mitochondria. This system of linked near-equilibrium redox and phosphorylation potentials constitutes a framework of primitive metabolic control that is altered in a number of disease phenotypes. The alteration of such disease phenotypes by substrate availability is discussed, as well as the importance of a thorough grounding in basic kinetics and thermodynamics in designing new therapies to normalize the metabolic abnormalities that are the proximate cause of many common and some rare diseases states.
Collapse
Affiliation(s)
- Richard L Veech
- Laboratory of Metabolic Control, NIAAA, National Institutes of Health, Bethesda, Maryland 20892
| |
Collapse
|
26
|
Malucelli E, Lodi R, Martinuzzi A, Tonon C, Barbiroli B, Iotti S. Free Mg2+ concentration in the calf muscle of glycogen phosphorylase and phosphofructokinase deficiency patients assessed in different metabolic conditions by 31P MRS. DYNAMIC MEDICINE : DM 2005; 4:7. [PMID: 15938748 PMCID: PMC1166570 DOI: 10.1186/1476-5918-4-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2005] [Accepted: 06/06/2005] [Indexed: 11/25/2022]
Abstract
BACKGROUND The increase in cytosolic free Mg2+ occurring during exercise and initial recovery in human skeletal muscle is matched by a decrease in cytosolic pH as shown by in vivo phosphorus magnetic resonance spectroscopy (31P MRS). To investigate in vivo to what extent the homeostasis of intracellular free Mg2+ is linked to pH in human skeletal muscle, we studied patients with metabolic myopathies due to different disorders of glycogen metabolism that share a lack of intracellular acidification during muscle exercise. METHODS We assessed by 31P MRS the cytosolic pH and free magnesium concentration ([Mg2+]) in calf muscle during exercise and post-exercise recovery in two patients with McArdle's disease with muscle glycogen phosphorylase deficiency (McArdle), and two brothers both affected by Tarui's disease with muscle phosphofructokinase deficiency (PFK). RESULTS All patients displayed a lack of intracellular acidosis during muscle exercise. At rest only one PFK patient showed a [Mg2+] higher than the value found in control subjects. During exercise and recovery the McArdle patients did not show any significant change in free [Mg2+], while both PFK patients showed decreased free [Mg2+] and a remarkable accumulation of phosphomonoesters (PME). During initial recovery both McArdle patients showed a small increase in free [Mg2+] while in PFK patients the pattern of free [Mg2+] was related to the rate of PME recovery. CONCLUSION i) homeostasis of free [Mg2+] in human skeletal muscle is strongly linked to pH as shown by patients' [Mg2+] pattern during exercise; ii) the pattern of [Mg2+] during exercise and post-exercise recovery in both PFK patients suggests that [Mg2+] is influenced by the accumulation of the phosphorylated monosaccharide intermediates of glycogenolysis, as shown by the increased PME peak signal. iii) 31P MRS is a suitable tool for the in vivo assessment of free cytosolic [Mg2+] in human skeletal muscle in different metabolic conditions.
Collapse
Affiliation(s)
- Emil Malucelli
- Dipartimento di Medicina Clinica e Biotecnologia Applicata, Università di Bologna; Via Massarenti 9, 40138 Bologna, Italy
| | - Raffaele Lodi
- Dipartimento di Medicina Clinica e Biotecnologia Applicata, Università di Bologna; Via Massarenti 9, 40138 Bologna, Italy
| | - Andrea Martinuzzi
- Dipartimento di Medicina Clinica e Biotecnologia Applicata, Università di Bologna; Via Massarenti 9, 40138 Bologna, Italy
| | - Caterina Tonon
- Dipartimento di Medicina Clinica e Biotecnologia Applicata, Università di Bologna; Via Massarenti 9, 40138 Bologna, Italy
| | - Bruno Barbiroli
- Dipartimento di Medicina Clinica e Biotecnologia Applicata, Università di Bologna; Via Massarenti 9, 40138 Bologna, Italy
| | - Stefano Iotti
- Dipartimento di Medicina Clinica e Biotecnologia Applicata, Università di Bologna; Via Massarenti 9, 40138 Bologna, Italy
| |
Collapse
|
27
|
Dobson GP. Organ arrest, protection and preservation: natural hibernation to cardiac surgery. Comp Biochem Physiol B Biochem Mol Biol 2005; 139:469-85. [PMID: 15544969 DOI: 10.1016/j.cbpc.2004.06.002] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2004] [Revised: 06/01/2004] [Accepted: 06/06/2004] [Indexed: 11/16/2022]
Abstract
Cardiac surgery continues to be limited by an inability to achieve complete myocardial protection from ischemia-reperfusion injury. This paper considers the following questions: (1) what lessons can be learned from mammalian hibernators to improve current methods of human myocardial arrest, protection and preservation? and (2) can the human heart be pharmacologically manipulated during acute global ischemia to act more like the heart of a hibernating mammal? After reviewing the major entropy-slowing strategies of hibernation, a major player identified in the armortarium is maintenance of the membrane potential. The resting membrane potential of the hibernator's heart appears to be maintained close to its pre-torpid state of around -85 mV. In open-heart surgery, 99% of all surgical heart arrest solutions (cardioplegia) employ high potassium (>16 mM) which depolarises the membrane voltage from -85 to around -50 mV. However, depolarising potassium cardioplegia has been increasingly linked to myocyte and microvascular damage leading to functional loss during reperfusion. Our recent work has been borrowed from hibernation biology and is focused on a very different arrest strategy which 'clamps' the membrane near its resting potential and depresses O2 consumption from baseline by about 90%. The new 'polarising' cardioplegia incorporates adenosine and lidocaine (AL) as the arresting combination, not high potassium. Studies in the isolated rat heart show that AL cardioplegia delivered at 37 degrees C can arrest the heart for up to 4 h with 70-80% recovery of the cardiac output, 85-100% recovery of heart rate, systolic pressure and rate-pressure product and 70-80% of baseline coronary flows. Only 14% of hearts arrested with crystalloid St. Thomas' solution No. 2 cardioplegia survived after 4 h. In conclusion, maintenance of the myocardial membrane potential near or close to its resting state appears to be an important feature of the hibernator's heart that may find great utility in surgical arrest and cellular preservation strategies. Identifying and safely turning 'off' and 'on' the entropy-slowing genes to down-regulate the hibernator's heart and applying this to human organs and tissues remains a major challenge for future genomics and proteomics.
Collapse
Affiliation(s)
- Geoffrey P Dobson
- Department of Physiology and Pharmacology, School of Biomedical Sciences, James Cook University, Molecular Science Building, Townsville, Qld 4811, Australia.
| |
Collapse
|
28
|
Lecarpentier Y, Blanc FX, Quillard J, Hébert JL, Krokidis X, Coirault C. Statistical mechanics of myosin molecular motors in skeletal muscles. J Theor Biol 2005; 235:381-92. [PMID: 15882700 DOI: 10.1016/j.jtbi.2005.01.018] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2004] [Revised: 01/07/2005] [Accepted: 01/25/2005] [Indexed: 11/22/2022]
Abstract
Statistical mechanics provides the link between microscopic properties of matter and its bulk properties. The grand canonical ensemble formalism was applied to contracting rat skeletal muscles, the soleus (SOL, n = 30) and the extensor digitalis longus (EDL, n = 30). Huxley's equations were used to calculate force (pi) per single crossbridge (CB), probabilities of six steps of the CB cycle, and peak muscle efficiency (Eff(max)). SOL and EDL were shown to be in near-equilibrium (CB cycle affinity 2.5 kJ/mol) and stationary state (linearity between CB cycle affinity and myosin ATPase rate). The molecular partition function (z) was higher in EDL (1.126+/-0.005) than in SOL (1.050+/-0.003). Both pi and Eff(max) were lower in EDL (8.3+/-0.1 pN and 38.1+/-0.2%, respectively) than in SOL (9.2+/-0.1 pN and 42.3+/-0.2%, respectively). The most populated step of the CB cycle was the last detached state (D3) (probability P(D3): 0.890+/-0.004 in EDL and 0.953+/-0.002 in SOL). In each muscle group, both pi and Eff(max) linearly decreased with z and statistical entropy and increased with P(D3). We concluded that statistical mechanics and Huxley's formalism provided a powerful combination for establishing an analytical link between chemomechanical properties of CBs, molecular partition function and statistical entropy.
Collapse
Affiliation(s)
- Y Lecarpentier
- Service de Physiologie, Hôpital de Bicêtre, Assistance Publique-Hôpitaux de Paris, Le Kremlin-Bicêtre, France.
| | | | | | | | | | | |
Collapse
|
29
|
Li G, Xiang B, Dai G, Shaw A, Liu H, Yang B, Jackson M, Deslauriers R, Tian G. Tissue edema does not change gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA)-enhanced T1 relaxation times of viable myocardium. J Magn Reson Imaging 2005; 21:744-51. [PMID: 15906335 DOI: 10.1002/jmri.20330] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
PURPOSE To determine whether tissue edema changes gadolinium-diethylenetriamine pentaacetic acid (Gd-DTPA)-enhanced T1 relaxation times of the viable myocardium. MATERIALS AND METHODS A total of 16 isolated pig hearts were divided into four groups (N=4/group) and perfused in a Langendorff apparatus. Gd-DTPA was injected into the aortic perfusion line. Tissue edema was then induced by two hours of simultaneous arterial/venous perfusion (SAVP). Myocardial water content and T1 relaxation times were monitored throughout SAVP. The volumes of the extracellular and intracellular compartments were assessed using 31P MRS-detectable markers, phenylphosphonic acid (PPA) and dimethyl methylphosphonate (DMMP). RESULTS Tissue water content in both viable and infarcted myocardium increased significantly during two-hour SAVP. However, Gd-DTPA-enhanced T1 relaxation times of the viable myocardium remained relatively unchanged. Infarcted myocardium, on the other hand, exhibited significant T1 shortening during SAVP. Furthermore, SAVP resulted in significant expansions of both extracellular and intracellular compartments, but the ratio of the volumes of the two compartments remained relatively constant. CONCLUSION Tissue edema in the viable myocardium does not increase the relative distribution volume of the contrast agent. As a result, edema does not change Gd-DTPA-enhanced T1 relaxation times of the viable myocardium.
Collapse
Affiliation(s)
- Gang Li
- Institute for Biodiagnostics, National Research Council, Winnipeg, Canada
| | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Dobson GP, Jones MW. Adenosine and lidocaine: a new concept in nondepolarizing surgical myocardial arrest, protection, and preservation. J Thorac Cardiovasc Surg 2004; 127:794-805. [PMID: 15001909 DOI: 10.1016/s0022-5223(03)01192-9] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE Depolarizing potassium cardioplegia has been increasingly linked to left ventricular dysfunction, arrhythmia, and microvascular damage. We tested a new polarizing normokalemic cardioplegic solution employing adenosine and lidocaine as the arresting, protecting, and preserving cardioprotective combination. Adenosine hyperpolarizes the myocyte by A1 receptor activation, and lidocaine blocks the sodium fast channels. METHODS Isolated perfused rat hearts were switched from the working mode to the Langendorff (nonworking) mode and arrested for 30 minutes, 2 hours, or 4 hours with 200 micromol/L adenosine and 500 micromol/L lidocaine in Krebs-Henseleit buffer (10 mmol/L glucose, pH 7.7, at 37 degrees C) or modified St Thomas' Hospital solution no. 2, both delivered at 70 mm Hg and 37 degrees C (arrest temperature 22 degrees C to 35 degrees C). RESULTS Adenosine and lidocaine hearts achieved faster mechanical arrest in (25 +/- 2 seconds, n = 23) compared with St Thomas' Hospital solution hearts (70 +/- 5 seconds, n = 24; P=.001). After 30 minutes of arrest, both groups developed comparable aortic flow at approximately 5 minutes of reperfusion. After 2 and 4 hours of arrest (cardioplegic solution delivered every 20 minutes for 2 minutes at 37 degrees C), only 50% (4 of 8) and 14% (1 of 7) of St Thomas' Hospital solution hearts recovered aortic flow, respectively. All adenosine and lidocaine hearts arrested for 2 hours (n = 7) and 4 hours (n = 9) recovered 70% to 80% of their prearrest aortic flows. Similarly, heart rate, systolic pressures, and rate-pressure products recovered to 85% to 100% and coronary flows recovered to 70% to 80% of prearrest values. Coronary vascular resistance during delivery of cardioplegic solution was significantly lower (P <.05) after 2 and 4 hours in hearts arrested with adenosine and lidocaine cardioplegic solution compared with hearts arrested with St Thomas' Hospital solution. CONCLUSIONS We conclude that adenosine and lidocaine polarizing cardioplegic solution confers superior cardiac protection during arrest and recovery compared with hyperkalemic depolarizing St Thomas' Hospital cardioplegic solution.
Collapse
Affiliation(s)
- Geoffrey P Dobson
- Department of Physiology and Pharmacology, James Cook University, Molecular Science Building, Townsville, Queensland 4811, Australia.
| | | |
Collapse
|
31
|
Jansen MA, Shen H, Zhang L, Wolkowicz PE, Balschi JA. Energy requirements for the Na+ gradient in the oxygenated isolated heart: effect of changing the free energy of ATP hydrolysis. Am J Physiol Heart Circ Physiol 2003; 285:H2437-45. [PMID: 12958035 DOI: 10.1152/ajpheart.00534.2003] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This study tests the hypothesis that a decrease of the free energy of ATP hydrolysis (Delta GATP) below a threshold value will inhibit Na+-K+-ATPase (Na+ pump) activity and result in an increase of intracellular Na+ concentration ([Na+]i) in the heart. Conditions were designed in which hearts were solely dependent on ATP derived from oxidative phosphorylation. The only substrate supplied was the fatty acid butyrate (Bu) at either low, 0.1 mM (LowBu), or high, 4 mM (HighBu), concentrations. Escalating work demand reduced the Delta GATP of the LowBu hearts. 31P, 23Na, and 87Rb NMR spectroscopy measured high-energy phosphate metabolites, [Na+]i, and Rb+ uptake. Rb+ uptake was used to estimate Na+ pump activity. To measure [Na+]i using a shift reagent for cations, extracellular Ca2+ was reduced to 0.85 mM, which eliminated work demand Delta GATP reductions. Increasing extracellular Na+ (Nae+) to 200 mM restored work demand Delta GATP reductions. In response to higher [Na+]e, [Na+]i increased equally in LowBu and HighBu hearts to approximately 8.6 mM, but Delta GATP decreased only in LowBu hearts. At lowest work demand the LowBu heart Delta GATP was -53 kJ/mol, Rb+ uptake was similar to that of HighBu hearts, and [Na+]i was constant. At highest work demand the LowBu heart Delta GATP decreased to -48 kJ/mol, the [Na+]i increased to 25 mM, and Rb+ uptake was 56% of that in HighBu hearts. At the highest work demand the HighBu heart Delta GATP was -54 kJ/mol and [Na+]i increased only approximately 10%. We conclude that a Delta GATP below -50 kJ/mol limits the Na+ pump and prevents maintenance of [Na+]i homeostasis.
Collapse
Affiliation(s)
- Maurits A Jansen
- Division of Cardiovascular Disease, Department o fMedicine, Universityof Alabama, Birmingham, 35294-4470, USA
| | | | | | | | | |
Collapse
|
32
|
Noda C, Masuda T, Sato K, Ikeda K, Shimohama T, Matsuyama N, Izumi T. Vanadate improves cardiac function and myocardial energy metabolism in diabetic rat hearts. ACTA ACUST UNITED AC 2003; 44:745-57. [PMID: 14587656 DOI: 10.1536/jhj.44.745] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Vanadium mimicking the metabolic effects of insulin is known to decrease serum glucose levels and to influence glucose metabolism in diabetes mellitus. However, it is unclear whether vanadium ameliorates the metabolic disorder in diabetic hearts causing myocardial dysfunction. The purpose of this study was to assess the effects of vanadium on cardiac performance and energy metabolism in diabetic rat hearts. Four groups of Wistar rats were studied: untreated control rats (group C, n = 8). vanadate-treated rats (group V, n = 10), untreated diabetic rats (group DM, n = 9) induced by streptozotocin. and vanadate-treated diabetic rats (group DMV, n = 8). Vanadate-treated rats drank a 1.5 mM sodium orthovanadate (Na3VO4) solution during a 4 week diabetic condition. Hearts were perfused with Krebs-Henseleit buffer after the diabetic duration. After the maximum left ventricular dP/dt and cardiac efficiency were calculated, the myocardial contents of ATP and creatine phosphate (P-Cr) and myocardial energy metabolism were assessed by cytosolic phosphorylation potential. Peak positive and negative dP/dt, and cardiac efficiency decreased significantly in group DM compared with group C, while there were no significant differences between groups C and DMV. The myocardial contents of ATP (micromol/g wet heart) and P-Cr (micromol/g wet heart), and cytosolic phosphorylation potential (M(-1)) increased from 2.72 +/- 0.46. 1.45 +/- 0.58. and 3,530 +/- 1,220 in group DM to 3.88 +/- 0.76, 3.81 +/- 1.36, and 11,200 +/- 2,400 in group DMV, respectively. It is concluded that vanadium restored the production of high energy phosphates in the myocardium and improved myocardial dysfunction by regulating metabolic processes in diabetic rat hearts.
Collapse
Affiliation(s)
- Chiharu Noda
- Department of Internal Medicine, Kitasato University School of Medicine, Sagamihara, Kanagawa 228-8555, Japan
| | | | | | | | | | | | | |
Collapse
|
33
|
Masuda T, Sato K, Noda C, Ikeda KM, Matsunaga A, Ogura MN, Shimizu K, Nagasawa H, Matsuyama N, Izumi T. Protective effect of urinary trypsin inhibitor on myocardial mitochondria during hemorrhagic shock and reperfusion. Crit Care Med 2003; 31:1987-92. [PMID: 12847393 DOI: 10.1097/01.ccm.0000057037.44171.ba] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
OBJECTIVE To examine the mitochondrial function in the myocardium after hemorrhagic shock and reperfusion and to evaluate the protective effect of urinary trypsin inhibitor (UTI) on mitochondria. DESIGN Animal experiment. SETTING University research laboratory. SUBJECTS Wistar rats receiving 50,000 units/kg/hr of UTI (n = 27; UTI group) and control rats (n = 26; control group). INTERVENTIONS Rats were subjected to low-perfusion ischemia with the left ventricular systolic pressure maintained at 50 mm Hg for 60 mins by bleeding, followed by a 60-min reperfusion by transfusion of shed blood. UTI was infused continuously from 10 mins before bleeding. Cardiac function was measured before bleeding, after bleeding, and after transfusion; at each determination point, the myocardial contents of adenosine triphosphate (ATP), creatine phosphate (P-Cr), pyruvate (Pyr), and lactate (Lac) were measured enzymatically. The cytosolic phosphorylation potential (PP) as well as the redox potential of the oxidized form of nicotinamide adenine dinucleotide/reduced form of nicotinamide adenine dinucleotide couple in mitochondria (Eh(NAD+/NADH)) and change of Gibbs free energy in ATP hydrolysis (deltaG(ATP hydrolysis) energy) were calculated. MEASUREMENTS AND MAIN RESULTS Cardiac function decreased during hemorrhagic shock but improved significantly in the UTI group after transfusion compared with the control group. Lac and the Lac/Pyr ratio were significantly lower in the UTI group than in the control group after transfusion. ATP and P-Cr were significantly higher in the UTI group than in the control group after transfusion. PP (x10(3) M-1), Eh(NAD+/NADH) (x - 1 mV), and deltaG(ATP hydrolysis) (x - 1 kcal/mol) were 1.9 +/- 0.4, 266 +/- 4, and 9.7 +/- 0.2, respectively, in the control group and 4.0 +/- 0.9, 274 +/- 5 and 13.0 +/- 0.2, respectively, in the UTI group after transfusion (p <.001, p <.001, and p <.001, respectively). CONCLUSIONS In reperfusion after hemorrhagic shock, oxidative phosphorylation in myocardial mitochondria is impaired and energy production remains reduced, even after reperfusion. UTI contributed to the recovery of cardiac function after reperfusion, probably by reducing the severity of mitochondrial dysfunction during a state of shock and by maintaining energy production.
Collapse
Affiliation(s)
- Takashi Masuda
- Department of Rehabilitation, School of Allied Helath Sciences, Kitasato University, Sagamihara, Kanagawa, Japan.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
34
|
Obrosova IG, Van Huysen C, Fathallah L, Cao XC, Greene DA, Stevens MJ. An aldose reductase inhibitor reverses early diabetes-induced changes in peripheral nerve function, metabolism, and antioxidative defense. FASEB J 2002; 16:123-5. [PMID: 11709499 DOI: 10.1096/fj.01-0603fje] [Citation(s) in RCA: 160] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Aldose reductase inhibitors (ARIs) prevent peripheral nerve dysfunction and morphological abnormalities in diabetic animal models. However, some experimental intervention studies and clinical trials of ARIs on diabetic neuropathy appeared disappointing because of either 1) their inadequate design and, in particular, insufficient correction of the sorbitol pathway activity or 2) the inability to reverse established functional and metabolic deficits of diabetic neuropathy by AR inhibition in general. We evaluated whether diabetes-induced changes in nerve function, metabolism, and antioxidative defense are corrected by the dose of ARI (sorbinil, 65 mg/kg/d in the diet), resulting in complete inhibition of increased sorbitol pathway activity. The groups included control rats and streptozotocin-diabetic rats treated with/without ARI for 2 weeks after 4 weeks of untreated diabetes. ARI treatment corrected diabetes-induced nerve functional changes; that is, decrease in endoneurial nutritive blood flow, motor and sensory nerve conduction velocities, and metabolic abnormalities (i.e., mitochondrial and cytosolic NAD+/NADH redox imbalances and energy deficiency). ARI restored nerve concentrations of two major non-enzymatic antioxidants, reduced glutathione (GSH) and ascorbate, and completely arrested diabetes-induced lipid peroxidation. In conclusion, treatment with adequate doses of ARIs (that is, doses that completely inhibit increased sorbitol pathway activity) is an effective approach for reversal of, at least, early diabetic neuropathy.
Collapse
Affiliation(s)
- Irina G Obrosova
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, Michigan 48109-0354, USA.
| | | | | | | | | | | |
Collapse
|
35
|
Kemp GJ, Roussel M, Bendahan D, Le Fur Y, Cozzone PJ. Interrelations of ATP synthesis and proton handling in ischaemically exercising human forearm muscle studied by 31P magnetic resonance spectroscopy. J Physiol 2001; 535:901-28. [PMID: 11559784 PMCID: PMC2278815 DOI: 10.1111/j.1469-7793.2001.00901.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2000] [Accepted: 05/14/2001] [Indexed: 11/26/2022] Open
Abstract
1. In ischaemic exercise ATP is supplied only by glycogenolysis and net splitting of phosphocreatine (PCr). Furthermore, 'proton balance' involves only glycolytic lactate/H+ generation and net H+ 'consumption' by PCr splitting. This work examines the interplay between these, metabolic regulation and the creatine kinase equilibrium. 2. Nine male subjects (age 25-45 years) performed finger flexion (7 % maximal voluntary contraction at 0.67 Hz) under cuff ischaemia. 31P magnetic resonance spectra were acquired from finger flexor muscle in a 4.7 T magnet using a 5 cm surface coil. 3. Initial PCr depletion rate estimates total ATP turnover rate; glycolytic ATP synthesis was obtained from this and changes in [PCr], and then used to obtain flux through 'distal' glycolysis (phosphofructokinase and beyond) to lactate; 'proximal' flux (through phosphorylase) was obtained from this and changes in [phosphomonoester]. Total H+ load (lactate load less H+ consumption) was used to estimate cytosolic buffer capacity (beta). 4. Glycolytic ATP synthesis increased from near zero while PCr splitting declined. Net H+ load was approximately linear with pH, suggesting beta = 20 mmol x l(-1) (pH unit)(-1) at rest, increasing as pH falls. 5. Relationships between glycolytic rate and changes in [PCr] (i.e. the time-integrated mismatch between ATP use and production), and thus also [P(i)] (substrate for phosphorylase), suggest that increase in glycolysis is due partly to 'open-loop' Ca2+-dependent conversion of phosphorylase b to a, and partly to the 'closed loop' increase in P(i) consequent on net PCr splitting. 6. The 'settings' of these mechanisms have a strong influence on changes in pH and metabolite concentrations.
Collapse
Affiliation(s)
- G J Kemp
- Department of Musculoskeletal Science, University of Liverpool, Liverpool L69 3GA, UK.
| | | | | | | | | |
Collapse
|
36
|
Metzler DE, Metzler CM, Sauke DJ. Lipids, Membranes, and Cell Coats. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50011-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
|
37
|
McMillen J, Donovan CM, Messer JI, Willis WT. Energetic driving forces are maintained in resting rat skeletal muscle after dietary creatine supplementation. J Appl Physiol (1985) 2001; 90:62-6. [PMID: 11133894 DOI: 10.1152/jappl.2001.90.1.62] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The total creatine (TCr) pool of skeletal muscle is composed of creatine (Cr) and phosphocreatine (PCr). In resting skeletal muscle, the ratio of PCr to TCr (PCr/TCr; PCr energy charge) is approximately 0.6-0.8, depending on the fiber type. PCr/TCr is linked to the cellular free energy of ATP hydrolysis by the Cr kinase equilibrium. Dietary Cr supplementation increases TCr in skeletal muscle. However, many previous studies have reported data indicating that PCr/TCr falls after supplementation, which would suggest that Cr supplementation alters the resting energetic state of myocytes. This study investigated the effect of Cr supplementation on the energy phosphates of resting skeletal muscle. Male rats were fed either rodent chow (control) or chow supplemented with 2% (wt/wt) Cr. After 2 wk on the diet, the gastrocnemius and soleus muscles were freeze clamped and removed from anesthetized animals. Cr supplementation increased TCr, PCr, and Cr levels in the gastrocnemius by 20, 22, and 17%, respectively (P < 0.05). A numerical 6% higher mean soleus TCr in Cr-supplemented rats was not statistically significant. All other energy phosphate concentrations, free energy of ATP hydrolysis, and PCr/TCr were not different between the two groups in either muscle. We conclude that Cr supplementation simply increased TCr in fast-twitch rat skeletal muscle but did not otherwise alter resting cellular energetic state.
Collapse
Affiliation(s)
- J McMillen
- Exercise and Sport Research Institute, Arizona State University, Tempe, Arizona 85287, USA
| | | | | | | |
Collapse
|
38
|
Abstract
The cost of living can be measured as an animal's metabolic rate. Basal metabolic rate (BMR) is factorially related to other metabolic rates. Analysis of BMR variation suggests that metabolism is a series of linked processes varying in unison. Membrane processes, such as maintenance of ion gradients, are important costs and components of BMR. Membrane bilayers in metabolically active systems are more polyunsaturated and less monounsaturated than metabolically less-active systems. Such polyunsaturated membranes have been proposed to result in an increased molecular activity of membrane proteins, and in this manner the amount of membrane and its composition can act as a pacemaker for metabolism. The potential importance of membrane acyl composition in metabolic depression, hormonal control of metabolism, the evolution of endothermy, as well as its implications for lifespan and human health, are briefly discussed.
Collapse
Affiliation(s)
- A J Hulbert
- Department of Biological Science, University of Wollongong, NSW, Australia.
| | | |
Collapse
|
39
|
Obrosova IG, Van Huysen C, Fathallah L, Cao X, Stevens MJ, Greene DA. Evaluation of α 1‐adrenoceptor antagonist on diabetes‐induced changes in peripheral nerve function, metabolism, and antioxidative defense. FASEB J 2000. [DOI: 10.1096/fj.99-0803com] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Irina G. Obrosova
- Division of Endocrinology and MetabolismDepartment of Internal MedicineUniversity of Michigan Medical CenterAnn ArborMichigan48109‐0354USA
| | - Carol Van Huysen
- Division of Endocrinology and MetabolismDepartment of Internal MedicineUniversity of Michigan Medical CenterAnn ArborMichigan48109‐0354USA
| | - Lamia Fathallah
- Division of Endocrinology and MetabolismDepartment of Internal MedicineUniversity of Michigan Medical CenterAnn ArborMichigan48109‐0354USA
| | - Xianghui Cao
- Division of Endocrinology and MetabolismDepartment of Internal MedicineUniversity of Michigan Medical CenterAnn ArborMichigan48109‐0354USA
| | - Martin J. Stevens
- Division of Endocrinology and MetabolismDepartment of Internal MedicineUniversity of Michigan Medical CenterAnn ArborMichigan48109‐0354USA
| | - Douglas A. Greene
- Division of Endocrinology and MetabolismDepartment of Internal MedicineUniversity of Michigan Medical CenterAnn ArborMichigan48109‐0354USA
| |
Collapse
|
40
|
Astore D, Boicelli CA. Hyperammonemia and chronic hepatic encephalopathy: an in vivo PMRS study of the rat brain. MAGMA (NEW YORK, N.Y.) 2000; 10:160-6. [PMID: 10873206 DOI: 10.1007/bf02590641] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The brain energy metabolism of rats affected by chronic hepatic encephalopathy due to portacaval shunting was monitored by in vivo 31P-nuclear magnetic resonance spectroscopy before and after ammonium acetate administration. With respect to healthy unoperated and to sham operated controls, portacaval shunting decreased the levels of the nuclear magnetic resonance (NMR) visible brain phosphocreatine and nucleoside phosphates, and the intracellular [free Mg(2+)]. Ammonium acetate induced a further decrease of the levels of the NMR detectable phosphocreatine and nucleoside triphosphates and of the [free Mg(2+)], while the PMR spectra of the brain of non-shunted rats did not show any significant change even after treatment with ammonium acetate.
Collapse
Affiliation(s)
- D Astore
- Vascular Surgery, IRCCS H San Raffaele, Milan, Italy
| | | |
Collapse
|
41
|
Iotti S, Frassineti C, Alderighi L, Sabatini A, Vacca A, Barbiroli B. In vivo (31)P-MRS assessment of cytosolic [Mg(2+)] in the human skeletal muscle in different metabolic conditions. Magn Reson Imaging 2000; 18:607-14. [PMID: 10913722 DOI: 10.1016/s0730-725x(00)00132-6] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Cytosolic free [Mg(2+)] can be assessed in vivo by (31)P-MRS from the chemical shift of beta-ATP. The reliability of in vivo measurements depends on the availability of appropriate in vitro calibration curves obtained by using solutions that mimic the in vivo cytosolic conditions as far as possible. We build a semi-empiric equation that correlates the chemical shift of beta-ATP to free [Mg(2+)] taking into account the amount of Mg(2+) bound to all other ligands in solution. Our experiments resulted in a reliable ten-parameters equation directly usable to assess the cytosolic free [Mg(2+)] of human skeletal muscle at rest, during work and recovery. Our experiments also resulted in a new equation that allows the assessment of cytosolic pH from the chemical shift of Pi taking into account the measured free [Mg(2+)]. To perform simultaneous calculation of free [Mg(2+)] and pH in the skeletal muscle in different metabolic conditions we developed a specific software package available on Internet (http://www.unibo.it/bioclin) together with another program based on the equation previously obtained to calculate cytosolic free [Mg(2+)] in the human brain. The reliability and effectiveness of our equations and software were tested on the calf muscles of healthy volunteers at rest, during work and recovery.
Collapse
Affiliation(s)
- S Iotti
- Biochimica Clinica, Dipartimento di Medicina Clinica e Biotecnologia applicata "D Campanacci," Università di Bologna, Italy.
| | | | | | | | | | | |
Collapse
|
42
|
Obrosova IG, Fathallah L, Lang HJ. Interaction between osmotic and oxidative stress in diabetic precataractous lens: studies with a sorbitol dehydrogenase inhibitor. Biochem Pharmacol 1999; 58:1945-54. [PMID: 10591149 DOI: 10.1016/s0006-2952(99)00315-9] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Both sorbitol accumulation-linked osmotic stress and "pseudohypoxia" [increase in NADH/NAD+, similar to that in hypoxic tissues, and attributed to increased sorbitol dehydrogenase (1-iditol:NAD+ 5-oxidoreductase; EC 1.1.1.14; SDH) activity] have been invoked among the mechanisms underlying oxidative injury in target tissues for diabetic complications. We used the specific SDH inhibitor SDI-157 [2-methyl-4(4-N,N-dimethylaminosulfonyl-1-piperazino)pyrimid ine] to evaluate the role of osmotic stress versus "pseudohypoxia" in oxidative stress occurring in diabetic precataractous lens. Control and diabetic rats were treated with or without SDI-157 (100 mg/kg/day for 3 weeks). Lens malondialdehyde (MDA) plus 4-hydroxyalkenals (4-HA), MDA, GSH, and ascorbate levels, as well as the GSSG/GSH ratios, were similar in SDI-treated and untreated control rats, thus indicating that SDI-157 was not a prooxidant. Intralenticular osmotic stress, manifested by sorbitol levels, was more severe in SDI-treated diabetic rats (38.2+/-6.8 vs 21.2+/-3.5 micromol/g in untreated diabetic and 0.758+/-0.222 micromol/g in control rats, P<0.01 for both), while the decrease in the free cytosolic NAD+/NADH ratio was partially prevented (120+/-16 vs 88+/-11 in untreated diabetic rats and 143+/-13 in controls, P<0.01 for both). GSH and ascorbate levels were decreased, while MDA plus 4-HA and MDA levels were increased in diabetic rats versus controls; both antioxidant depletion and lipid aldehyde accumulation were exacerbated by SDI treatment. Superoxide dismutase (superoxide:superoxide oxidoreductase; EC 1.15.1.1), GSSG reductase (NAD[P]H:oxidized-glutathione oxidoreductase; EC 1.6.4.2), GSH transferase (glutathione S-transferase; EC 2.5.1.18), GSH peroxidase (glutathione:hydrogen-peroxide oxidoreductase; EC 1.11.1.9), and cytoplasmic NADH oxidase activities were increased in diabetic rats versus controls, and all the enzymes but GSH peroxidase were up-regulated further by SDI. In conclusion, sorbitol accumulation and osmotic stress generated oxidative stress in diabetic lens, whereas the contribution of "pseudohypoxia" was minor. SDIs provide a valuable tool for exploring mechanisms of oxidative injury in sites of diabetic complications.
Collapse
Affiliation(s)
- I G Obrosova
- Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor 48109-0678, USA.
| | | | | |
Collapse
|
43
|
Barbiroli B, Iotti S, Cortelli P, Martinelli P, Lodi R, Carelli V, Montagna P. Low brain intracellular free magnesium in mitochondrial cytopathies. J Cereb Blood Flow Metab 1999; 19:528-32. [PMID: 10326720 DOI: 10.1097/00004647-199905000-00007] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The authors studied, by in vivo phosphorus magnetic resonance spectroscopy (31P-MRS), the occipital lobes of 19 patients with mitochondrial cytopathies to clarify the functional relation between energy metabolism and concentration of cytosolic free magnesium. All patients displayed defective mitochondrial respiration with low phosphocreatine concentration [PCr] and high inorganic phosphate concentration [Pi] and [ADP]. Cytosolic free [Mg2+] and the readily available free energy (defined as the actual free energy released by the exoergonic reaction of ATP hydrolysis, i.e., deltaG(ATPhyd)) were abnormally low in all patients. Nine patients were treated with coenzyme Q10 (CoQ), which improved the efficiency of the respiratory chain, as shown by an increased [PCr], decreased [Pi] and [ADP], and increased availability of free energy (more negative value of deltaG(ATPhyd)). Treatment with CoQ also increased cytosolic free [Mg2+] in all treated patients. The authors findings demonstrate low brain free [Mg2+] in our patients and indicate that it resulted from failure of the respiratory chain. Free Mg2+ contributes to the absolute value of deltaG(ATPhyd). The results also are consistent with the view that cytosolic [Mg2+] is regulated in the intact brain cell to equilibrate, at least in part, any changes in rapidly available free energy.
Collapse
Affiliation(s)
- B Barbiroli
- Biochimica Clinica, Dipartimento di Medicina Clinica e Biotecnologia Applicata D. Campanacci, Bologna, Italy
| | | | | | | | | | | | | |
Collapse
|
44
|
Barbiroli B, Martinelli P, Patuelli A, Lodi R, Iotti S, Cortelli P, Montagna P. Phosphorus magnetic resonance spectroscopy in multiple system atrophy and Parkinson's disease. Mov Disord 1999; 14:430-5. [PMID: 10348465 DOI: 10.1002/1531-8257(199905)14:3<430::aid-mds1007>3.0.co;2-s] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
We performed in vivo phosphorus magnetic resonance spectroscopy on the occipital lobes of 15 patients with multiple system atrophy (MSA; eight with olivopontocerebellar atrophy [OPCA] and seven with the striatonigral degeneration variant [SND]), 13 patients with idiopathic Parkinson's disease (PD), and 16 age-matched healthy subjects. The MSA group showed significantly reduced phosphocreatine (PCr), increased inorganic phosphate (Pi), and unchanged cytosolic free [Mg2+], and pH. We did not find any significant difference between the OPCA and SND variants. However, patients with PD showed significantly increased content of Pi, decreased cytosolic free [Mg2+], and unchanged [PCr] and pH. Comparing the MSA and PD groups, [PCr] was significantly lower in MSA than in PD, whereas cytosolic free [Mg2+] was significantly lower in PD. Despite a certain degree of overlap of [PCr] and [Mg2+] values between the two groups, by considering both variables at the same time it was possible to classify correctly 93% of cases by discriminant analysis. We conclude that phosphorus magnetic resonance spectroscopy discloses abnormal phosphate metabolite and ion contents in both MSA and PD, respectively, and may provide noninvasive diagnostic help to differentiate MSA from PD.
Collapse
Affiliation(s)
- B Barbiroli
- Biochimica Clinica, Dipartimento di Medicina Clinica e Biotecnologia Applicata D. Campanacci, Università di Bologna, Italy
| | | | | | | | | | | | | |
Collapse
|
45
|
Befroy DE, Powell T, Radda GK, Clarke K. Osmotic shock: modulation of contractile function, pHi, and ischemic damage in perfused guinea pig heart. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:H1236-44. [PMID: 10199848 DOI: 10.1152/ajpheart.1999.276.4.h1236] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To determine the contribution of changes in extracellular osmolarity to ischemic injury, isolated guinea pig hearts were perfused with hyposmotic (220 mosM) or hyperosmotic (380 mosM) buffer. 31P NMR spectroscopy was used to follow changes in intracellular pH (pHi) and energetics. Hyposmotic buffer decreased myocardial developed pressure by 30 +/- 2% and pHi by 0.02 +/- 0.01 unit, whereas hyperosmotic buffer increased myocardial developed pressure by 34 +/- 1% and pHi by 0.14 +/- 0.01 unit. All hearts recovered to control values on restoration of isosmotic (300 mosM) buffer. The hyperosmolar-induced intracellular alkalosis and developed pressure increase were not prevented by inhibition of Na+/H+ exchange with use of 1 microM HOE-642 but were abolished with use of bicarbonate-free buffers. After 20 min of total global ischemia, hearts perfused with hyposmotic buffer showed significantly greater recoveries of developed pressure, phosphocreatine, and ATP than control hearts, but hearts perfused with hyperosmotic buffer did not recover after ischemia. In conclusion, buffer osmolarities between 220 and 380 mosM alter myocardial pHi and developed pressure but are not deleterious during perfusion. However, buffer osmolarity significantly alters the extent of myocardial ischemic injury.
Collapse
Affiliation(s)
- D E Befroy
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
| | | | | | | |
Collapse
|
46
|
Barbiroli B, Iotti S, Lodi R. Aspects of human bioenergetics as studied in vivo by magnetic resonance spectroscopy. Biochimie 1998; 80:847-53. [PMID: 9893943 DOI: 10.1016/s0300-9084(00)88879-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We outline the relevant capabilities of in vivo phosphorus MR spectroscopy by discussing some aspects of normal human biochemistry as studied by this technique. The transport of inorganic phosphate from cytosol into mitochondria in the human skeletal muscle was studied by exploiting a new experimental protocol. We found that Pi was transported into mitochondria in the absence of ATP biosynthesis and in the presence of a pH gradient. The control of CoQ on the efficiency of oxidative phosphorylation in the skeletal muscle and brain was studied by administering CoQ to patients with mitochondrial cytopathies due to known enzyme defects. Before CoQ we had detected a relevant reduction of mitochondrial functionality in the skeletal muscle as shown by the reduced rate of phosphocreatine recovery from exercise, and in the occipital lobes by reduced [phosphocreatine] and a high [ADP] and [Pi]. After CoQ all brain variables were remarkably improved. Treatment with CoQ also improved the rate of muscle phosphocreatine recovery from exercise. Our in vivo findings support the hypothesis that the concentration of CoQ rather than the rate of its lateral diffusion in the mitochondrial membrane controls the efficiency of oxidative phosphorylation. Other experiments were undertaken to clarify the functional relationship between cytosolic free [Mg2+] and cell bioenergetics in the intact human brain. In the same group of patients with mitochondrial cytopathies we found decreased delta G of ATP hydrolysis and low cytosolic free [Mg2+]. Treatment with CoQ resulted in improved brain bioenergetics and increased free [Mg2+]. These findings strongly indicate that decreased free magnesium was secondary to defective mitochondrial respiration, and support the hypothesis that cytosolic free [Mg2+] is regulated in the intact brain cell to equilibrate, at least in part, any changes in rapidly available free energy.
Collapse
Affiliation(s)
- B Barbiroli
- Dipartimento di Medicina Clinica e Biotecnologia Applicata (D Campanacci), Bologna, Italy
| | | | | |
Collapse
|
47
|
Headrick JP, McKirdy JC, Willis RJ. Functional and metabolic effects of extracellular magnesium in normoxic and ischemic myocardium. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 275:H917-29. [PMID: 9724296 DOI: 10.1152/ajpheart.1998.275.3.h917] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Metabolic and functional responses to extracellular Mg2+ concentration ([Mg2+]o) were studied in perfused rat heart. Elevations of [Mg2+]o from 1.2 to 2.4, 5.0, and 8.0 mM dose dependently reduced contractile function and myocardial oxygen consumption (MVO2) up to 80%. Intracellular Mg2+ concentration ([Mg2+]i) remained stable (0.45-0.50 mM) during perfusion with 1.2-5. 0 mM [Mg2+]o but increased to 0.81 +/- 0.14 mM with 8.0 mM [Mg2+]o. Myocardial ATP was unaffected by [Mg2+]o, phosphocreatine (PCr) increased up to 25%, and Pi declined by up to 50%. Free energy of ATP hydrolysis (DeltaGATP) increased from -60 to -64 kJ/mol. Adenosine efflux declined in parallel with changes in MVO2 and [AMP]. At comparable workload and MVO2, the effects of [Mg2+]o on cytosolic free energy were mimicked by reduced extracellular Ca2+ concentration ([Ca2+]o) or Ca2+ antagonism with verapamil. Moreover, functional and energetic effects of [Mg2+]o were reversed by elevated [Ca2+]o. Despite similar reductions in preischemic function and MVO2, metabolic and functional recovery from 30 min of global ischemia was enhanced in hearts treated with 8.0 mM [Mg2+]o vs. 2.0 microM verapamil. It is concluded that 1) 1.2-8.0 mM [Mg2+]o improves myocardial cytosolic free energy indirectly by reducing metabolic rate and Ca2+ entry; 2) [Mg2+]i does not respond rapidly to elevations in [Mg2+]o from 1.2 to 5.0 mM and is uninvolved in acute functional and metabolic responses to [Mg2+]o; 3) adenosine formation in rat heart is indirectly reduced during elevated [Mg2+]o; and 4) 8.0 mM [Mg2+]o provides superior protection during ischemia-reperfusion compared with functionally equipotent Ca2+ channel blockade.
Collapse
Affiliation(s)
- J P Headrick
- Rotary Centre for Cardiovascular Research, School of Health Science, Griffith University Gold Coast Campus, Southport, Queensland 4217, Australia
| | | | | |
Collapse
|
48
|
Ramasamy R, Trueblood N, Schaefer S. Metabolic effects of aldose reductase inhibition during low-flow ischemia and reperfusion. THE AMERICAN JOURNAL OF PHYSIOLOGY 1998; 275:H195-203. [PMID: 9688914 DOI: 10.1152/ajpheart.1998.275.1.h195] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Several studies have shown that maintenance of glycolysis limits the metabolic and functional consequences of low-flow ischemia. Because diabetic animals are known to have impaired glycolytic metabolism coupled with increased flux through the aldose reductase (AR) pathway, we hypothesized that inhibition of AR would enhance glycolysis and thereby improve metabolic and functional recovery during low-flow ischemia. Hearts (n = 12) from nondiabetic control and diabetic rats were isolated and retrograde perfused using 11 mM glucose with or without the AR inhibitor zopolrestat (1 microM). Hearts were subjected to 30 min of low-flow ischemia (10% of baseline flow) and 30 min of reperfusion. 31P NMR spectroscopy was used to monitor time-dependent changes in phosphocreatine (PCr), ATP, and intracellular pH. Changes in the cytosolic redox ratio of NADH to NAD+ were obtained by measuring the ratio of tissue lactate to pyruvate. Effluent lactate concentrations and oxygen consumption were determined from the perfusate. AR inhibition improved functional recovery in both control and diabetic hearts, coupled with a lower cytosolic redox state and greater effluent lactate concentrations during ischemia. ATP levels during ischemia were significantly higher in AR-inhibited hearts, as was recovery of PCr. In diabetic hearts, AR inhibition also limited acidosis during ischemia and normalized pH recovery on reperfusion. These data demonstrate that AR inhibition maintains higher levels of high-energy phosphates and improves functional recovery upon reperfusion in hearts subjected to low-flow ischemia, consistent with an increase in glycolysis. Accordingly, this approach of inhibiting AR offers a novel method for protecting ischemic myocardium.
Collapse
Affiliation(s)
- R Ramasamy
- Division of Cardiology, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA
| | | | | |
Collapse
|
49
|
Kashiwaya Y, King MT, Veech RL. Substrate signaling by insulin: a ketone bodies ratio mimics insulin action in heart. Am J Cardiol 1997; 80:50A-64A. [PMID: 9293956 DOI: 10.1016/s0002-9149(97)00458-x] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The administration of saturating doses of insulin to the glucose perfused, working rat heart acutely increased activity of the glucose transporter 4, GLUT 4, in the plasma membrane (equilibrating extracellular glucose and intracellular [glucose]), activated glycogen synthase (stimulating the rate of glycogen synthesis), and increased mitochondrial acetyl CoA production by the pyruvate dehydrogenase multienzyme complex. Unexpectedly, insulin increased cardiac hydraulic work but decreased net glycolytic flux and O2 consumption, improving net cardiac efficiency by 28%. These improvements in physiologic performance and metabolic efficiency resulted from reduction of the mitochondrial free [NAD+]/[NADH] and oxidation of mitochondrial [coenzyme Q]/[coenzyme QH2], increasing the energy of the proton gradient between cytosolic and mitochondrial phases and leading to a doubling of the cytosolic free [sigmaATP]/[sigmaADP][sigmaPi]. The acute metabolic effects of insulin were qualitatively duplicated by addition of a ratio of 4 mM D-beta-hydroxybutyrate and 1 mM acetoacetate, and the increase in the efficiency was the same as with addition of insulin. Addition of both insulin and ketones to the glucose perfusate increased the efficiency of cardiac hydraulic work by 35%. The ability of a physiologic ratio of ketone bodies to correct most of the metabolic defects of acute insulin deficiency suggests therapeutic roles for these natural substrates during periods of impaired cardiac performance and in insulin-resistant states.
Collapse
Affiliation(s)
- Y Kashiwaya
- Laboratory of Membrane Biology and Biophysics, NIAAA, Rockville, Maryland 20852, USA
| | | | | |
Collapse
|
50
|
Möller HE, Vermathen P, Rummeny E, Wörtler K, Wuisman P, Rössner A, Wörmann B, Ritter J, Peters PE. In vivo 31P NMR spectroscopy of human musculoskeletal tumors as a measure of response to chemotherapy. NMR IN BIOMEDICINE 1996; 9:347-358. [PMID: 9176889 DOI: 10.1002/(sici)1099-1492(199612)9:8<347::aid-nbm431>3.0.co;2-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The value of in vivo 31P NMR spectroscopy to provide indicators of response to cytostatic chemotherapy was studied in patients with malignant musculoskeletal tumors. Characteristics of untreated cancers were strong signals of PME and PDE, moderately increased Pi and low PCr. The intracellular pH was slightly alkaline. The intracellular concentration of free magnesium was 70% of that in muscle. Spectroscopic findings at different times of therapy were compared with the percentage of tumor necrosis after surgical resection in 28 patients. In follow-up studies, energy-rich phosphates declined in nonresponders, while PME, Pi and frequently PDE increased. Treatment response appeared to involve the reversal of these trends. In five responders, a biphasic pattern was observed, i.e. initially the spectrum changed into that of severely ischemic cell injury followed by a successive phase of apparent 'tumor activation'. Pretreatment levels of (PCr+Pi)/total phosphate > or = 0.35 and PCr/ alpha-NTP > or = 1.5, an accelerated increase in total low-energy phosphates/total high-energy phosphates (> or = 3.0%/day) after the initial drug application, and a long-term decrease (< or = -0.4%/day) during later therapy were highly indicative of tumor response to chemotherapy. Such spectroscopic predictors for treatment response proved to be superior to currently used indices such as tumor size.
Collapse
Affiliation(s)
- H E Möller
- Westfälische Wilhelms-Universität Münster, Institut für Physikalische Chemie, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|