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Azevedo RDSD, Falcão KVG, Almeida SMVD, Araújo MC, Silva-Filho RC, Souza Maia MBD, Amaral IPGD, Leite ACR, de Souza Bezerra R. The tissue-specific nature of physiological zebrafish mitochondrial bioenergetics. Mitochondrion 2024; 77:101901. [PMID: 38777222 DOI: 10.1016/j.mito.2024.101901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 04/27/2024] [Accepted: 05/15/2024] [Indexed: 05/25/2024]
Abstract
Zebrafish are a powerful tool to study a myriad of experimental conditions, including mitochondrial bioenergetics. Considering that mitochondria are different in many aspects depending on the tissue evaluated, in the zebrafish model there is still a lack of this investigation. Especially for juvenile zebrafish. In the present study, we examined whether different tissues from zebrafish juveniles show mitochondrial density- and tissue-specificity comparing brain, liver, heart, and skeletal muscle (SM). The liver and brain complex IV showed the highest O2 consumption of all ETC in all tissues (10x when compared to other respiratory complexes). The liver showed a higher potential for ROS generation. In this way, the brain and liver showed more susceptibility to O2- generation when compared to other tissues. Regarding Ca2+ transport, the brain showed greater capacity for Ca2+ uptake and the liver presented low Ca2+ uptake capacity. The liver and brain were more susceptible to producing NO. The enzymes SOD and Catalase showed high activity in the brain, whereas GPx showed higher activity in the liver and CS in the SM. TEM reveals, as expected, a physiological diverse mitochondrial morphology. The essential differences between zebrafish tissues investigated probably reflect how the mitochondria play a diverse role in systemic homeostasis. This feature may not be limited to normal metabolic functions but also to stress conditions. In summary, mitochondrial bioenergetics in zebrafish juvenile permeabilized tissues showed a tissue-specificity and a useful tool to investigate conditions of redox system imbalance, mainly in the liver and brain.
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Affiliation(s)
- Rafael David Souto de Azevedo
- Laboratório de Biologia Celular e Molecular, Universidade de Pernambuco - UPE, Campus Garanhuns, Garanhuns, PE, Brazil.
| | - Kivia Vanessa Gomes Falcão
- Departamento de Bioquímica, Universidade Federal de Pernambuco, Cidade Universitária, Recife, PE, Brazil
| | | | - Marlyete Chagas Araújo
- Departamento de Bioquímica, Universidade Federal de Pernambuco, Cidade Universitária, Recife, PE, Brazil
| | | | | | | | | | - Ranilson de Souza Bezerra
- Departamento de Bioquímica, Universidade Federal de Pernambuco, Cidade Universitária, Recife, PE, Brazil
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2
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Uslu C, Kapan E, Lyakhovich A. Cancer resistance and metastasis are maintained through oxidative phosphorylation. Cancer Lett 2024; 587:216705. [PMID: 38373691 DOI: 10.1016/j.canlet.2024.216705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 01/19/2024] [Accepted: 02/01/2024] [Indexed: 02/21/2024]
Abstract
Malignant tumors have increased energy requirements due to growth, differentiation or response to stress. A significant number of studies in recent years have described upregulation of mitochondrial genes responsible for oxidative phosphorylation (OXPHOS) in some tumors. Although OXPHOS is replaced by glycolysis in some tumors (Warburg effect), both processes can occur simultaneously during the evolution of the same malignancies. In particular, chemoresistant and/or cancer stem cells appear to find a way to activate OXPHOS and metastasize. In this paper, we discuss recent work showing upregulation of OXPHOS in chemoresistant tumors and cell models. In addition, we show an inverse correlation of OXPHOS gene expression with the survival time of cancer patients after chemotherapy and discuss combination therapies for resistant tumors.
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Affiliation(s)
- Cemile Uslu
- Sabanci University, Molecular Biology, Genetics and Bioengineering, Faculty of Engineering and Natural Sciences, Turkey
| | - Eda Kapan
- Sabanci University, Molecular Biology, Genetics and Bioengineering, Faculty of Engineering and Natural Sciences, Turkey
| | - Alex Lyakhovich
- Sabanci University, Molecular Biology, Genetics and Bioengineering, Faculty of Engineering and Natural Sciences, Turkey.
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Kuebart A, Gross K, Maicher C, Sonnenschein M, Raupach A, Schulz J, Truse R, Hof S, Marcus C, Vollmer C, Bauer I, Picker O, Relja B, Herminghaus A. Gemfibrozil Improves Microcirculatory Oxygenation of Colon and Liver without Affecting Mitochondrial Function in a Model of Abdominal Sepsis in Rats. Int J Mol Sci 2023; 25:262. [PMID: 38203431 PMCID: PMC10778839 DOI: 10.3390/ijms25010262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 12/15/2023] [Accepted: 12/21/2023] [Indexed: 01/12/2024] Open
Abstract
Recent studies observed, despite an anti-hyperlipidaemic effect, a positive impact of fibrates on septic conditions. This study evaluates the effects of gemfibrozil on microcirculatory variables, mitochondrial function, and lipid peroxidation levels with regard to its potential role as an indicator for oxidative stress in the colon and liver under control and septic conditions and dependencies on PPARα-mediated mechanisms of action. With the approval of the local ethics committee, 120 Wistar rats were randomly divided into 12 groups. Sham and septic animals were treated with a vehicle, gemfibrozil (30 and 100 mg/kg BW), GW 6471 (1 mg/kg BW, PPARα inhibitor), or a combination of both drugs. Sepsis was induced via the colon ascendens stent peritonitis (CASP) model. Then, 24 h post sham or CASP surgery, a re-laparotomy was performed. Measures of vital parameters (heart rate (HR), mean arterial pressure (MAP), and microcirculation (µHbO2)) were recorded for 90 min. Mitochondrial respirometry and assessment of lipid peroxidation via a malondialdehyde (MDA) assay were performed on colon and liver tissues. In the untreated sham animals, microcirculation remained stable, while pre-treatment with gemfibrozil showed significant decreases in the microcirculatory oxygenation of the colon. In the CASP animals, µHbO2 levels in the colon and the liver were significantly decreased 90 min after laparotomy. Pre-treatment with gemfibrozil prevented the microcirculatory aberrations in both organs. Gemfibrozil did not affect mitochondrial function and lipid peroxidation levels in the sham or CASP animals. Gemfibrozil treatment influences microcirculation depending on the underlying condition. Gemfibrozil prevents sepsis-induced microcirculatory aberrances in the colon and liver PPARα-independently. In non-septic animals, gemfibrozil impairs the microcirculatory variables in the colon without affecting those in the liver.
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Affiliation(s)
- Anne Kuebart
- Department of Anesthesiology, University Hospital Duesseldorf, Moorenstrasse 5, 40225 Duesseldorf, Germany; (A.K.)
| | - Katharina Gross
- Department of Anesthesiology, University Hospital Duesseldorf, Moorenstrasse 5, 40225 Duesseldorf, Germany; (A.K.)
| | - Charlotte Maicher
- Department of Anesthesiology, University Hospital Duesseldorf, Moorenstrasse 5, 40225 Duesseldorf, Germany; (A.K.)
| | - Max Sonnenschein
- Department of Anesthesiology, University Hospital Duesseldorf, Moorenstrasse 5, 40225 Duesseldorf, Germany; (A.K.)
| | - Annika Raupach
- Department of Anesthesiology, University Hospital Duesseldorf, Moorenstrasse 5, 40225 Duesseldorf, Germany; (A.K.)
| | - Jan Schulz
- Department of Anesthesiology, University Hospital Duesseldorf, Moorenstrasse 5, 40225 Duesseldorf, Germany; (A.K.)
| | - Richard Truse
- Department of Anesthesiology, University Hospital Duesseldorf, Moorenstrasse 5, 40225 Duesseldorf, Germany; (A.K.)
| | - Stefan Hof
- Department of Anesthesiology, University Hospital Duesseldorf, Moorenstrasse 5, 40225 Duesseldorf, Germany; (A.K.)
| | - Carsten Marcus
- Department of Anesthesiology, University Hospital Duesseldorf, Moorenstrasse 5, 40225 Duesseldorf, Germany; (A.K.)
| | - Christian Vollmer
- Department of Anesthesiology, University Hospital Duesseldorf, Moorenstrasse 5, 40225 Duesseldorf, Germany; (A.K.)
| | - Inge Bauer
- Department of Anesthesiology, University Hospital Duesseldorf, Moorenstrasse 5, 40225 Duesseldorf, Germany; (A.K.)
| | - Olaf Picker
- Department of Anesthesiology, University Hospital Duesseldorf, Moorenstrasse 5, 40225 Duesseldorf, Germany; (A.K.)
| | - Borna Relja
- Department of Trauma, Hand, Plastic and Reconstructive Surgery, Translational and Experimental Trauma Research, University Hospital Ulm, Ulm University, Albert-Einstein-Allee 23, 89081 Ulm, Germany
| | - Anna Herminghaus
- Department of Anesthesiology, University Hospital Duesseldorf, Moorenstrasse 5, 40225 Duesseldorf, Germany; (A.K.)
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Okoye CN, Koren SA, Wojtovich AP. Mitochondrial complex I ROS production and redox signaling in hypoxia. Redox Biol 2023; 67:102926. [PMID: 37871533 PMCID: PMC10598411 DOI: 10.1016/j.redox.2023.102926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 09/29/2023] [Accepted: 10/06/2023] [Indexed: 10/25/2023] Open
Abstract
Mitochondria are a main source of cellular energy. Oxidative phosphorylation (OXPHOS) is the major process of aerobic respiration. Enzyme complexes of the electron transport chain (ETC) pump protons to generate a protonmotive force (Δp) that drives OXPHOS. Complex I is an electron entry point into the ETC. Complex I oxidizes nicotinamide adenine dinucleotide (NADH) and transfers electrons to ubiquinone in a reaction coupled with proton pumping. Complex I also produces reactive oxygen species (ROS) under various conditions. The enzymatic activities of complex I can be regulated by metabolic conditions and serves as a regulatory node of the ETC. Complex I ROS plays diverse roles in cell metabolism ranging from physiologic to pathologic conditions. Progress in our understanding indicates that ROS release from complex I serves important signaling functions. Increasing evidence suggests that complex I ROS is important in signaling a mismatch in energy production and demand. In this article, we review the role of ROS from complex I in sensing acute hypoxia.
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Affiliation(s)
- Chidozie N Okoye
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Rochester, NY, 14642, USA
| | - Shon A Koren
- Department of Neurobiology, Harvard Medical School, Boston, MA, 02115, USA
| | - Andrew P Wojtovich
- Department of Anesthesiology and Perioperative Medicine, University of Rochester Medical Center, Rochester, NY, 14642, USA; Department of Pharmacology and Physiology, University of Rochester Medical Center, Rochester, NY, 14642, USA.
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Sadri S, Tomar N, Yang C, Audi SH, Cowley AW, Dash RK. Effects of ROS pathway inhibitors and NADH and FADH 2 linked substrates on mitochondrial bioenergetics and ROS emission in the heart and kidney cortex and outer medulla. Arch Biochem Biophys 2023; 744:109690. [PMID: 37429534 PMCID: PMC10528392 DOI: 10.1016/j.abb.2023.109690] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 07/06/2023] [Indexed: 07/12/2023]
Abstract
Mitochondria are major sources of reactive oxygen species (ROS), which play important roles in both physiological and pathological processes. However, the specific contributions of different ROS production and scavenging components in the mitochondria of metabolically active tissues such as heart and kidney cortex and outer medulla (OM) are not well understood. Therefore, the goal of this study was to determine contributions of different ROS production and scavenging components and provide detailed comparisons of mitochondrial respiration, bioenergetics, ROS emission between the heart and kidney cortex and OM using tissues obtained from the same Sprague-Dawley rat under identical conditions and perturbations. Specifically, data were obtained using both NADH-linked substrate pyruvate + malate and FADH2-linked substrate succinate followed by additions of inhibitors of different components of the electron transport chain (ETC) and oxidative phosphorylation (OxPhos) and other ROS production and scavenging systems. Currently, there is limited data available for the mitochondria of kidney cortex and OM, the two major energy-consuming tissues in the body only next to the heart, and scarce quantitative information on the interplay between mitochondrial ROS production and scavenging systems in the three tissues. The findings from this study demonstrate significant differences in mitochondrial respiratory and bioenergetic functions and ROS emission among the three tissues. The results quantify the rates of ROS production from different complexes of the ETC, identify the complexes responsible for variations in mitochondrial membrane depolarization and regulations of ROS production, and quantify the contributions of ROS scavenging enzymes towards overall mitochondrial ROS emission. These findings advance our fundamental knowledge of tissue-specific and substrate-dependent mitochondrial respiratory and bioenergetic functions and ROS emission. This is important given the critical role that excess ROS production, oxidative stress, and mitochondrial dysfunction in the heart and kidney cortex and OM play in the pathogenesis of cardiovascular and renal diseases, including salt-sensitive hypertension.
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Affiliation(s)
- Shima Sadri
- Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Namrata Tomar
- Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Chun Yang
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Said H Audi
- Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI, 53226, USA; Department of Biomedical Engineering, Marquette University, Milwaukee, WI, 53223, USA
| | - Allen W Cowley
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, 53226, USA; Cardiovascular Research Center, Medical College of Wisconsin, Milwaukee, WI, 53226, USA
| | - Ranjan K Dash
- Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI, 53226, USA; Department of Physiology, Medical College of Wisconsin, Milwaukee, WI, 53226, USA; Cardiovascular Research Center, Medical College of Wisconsin, Milwaukee, WI, 53226, USA; Department of Biomedical Engineering, Marquette University, Milwaukee, WI, 53223, USA.
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6
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Sadri S, Zhang X, Audi SH, Cowley Jr. AW, Dash RK. Computational Modeling of Substrate-Dependent Mitochondrial Respiration and Bioenergetics in the Heart and Kidney Cortex and Outer Medulla. FUNCTION 2023; 4:zqad038. [PMID: 37575476 PMCID: PMC10413947 DOI: 10.1093/function/zqad038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 07/11/2023] [Accepted: 07/17/2023] [Indexed: 08/15/2023] Open
Abstract
Integrated computational modeling provides a mechanistic and quantitative framework to characterize alterations in mitochondrial respiration and bioenergetics in response to different metabolic substrates in-silico. These alterations play critical roles in the pathogenesis of diseases affecting metabolically active organs such as heart and kidney. Therefore, the present study aimed to develop and validate thermodynamically constrained integrated computational models of mitochondrial respiration and bioenergetics in the heart and kidney cortex and outer medulla (OM). The models incorporated the kinetics of major biochemical reactions and transport processes as well as regulatory mechanisms in the mitochondria of these tissues. Intrinsic model parameters such as Michaelis-Menten constants were fixed at previously estimated values, while extrinsic model parameters such as maximal reaction and transport velocities were estimated separately for each tissue. This was achieved by fitting the model solutions to our recently published respirometry data measured in isolated rat heart and kidney cortex and OM mitochondria utilizing various NADH- and FADH2-linked metabolic substrates. The models were validated by predicting additional respirometry and bioenergetics data, which were not used for estimating the extrinsic model parameters. The models were able to predict tissue-specific and substrate-dependent mitochondrial emergent metabolic system properties such as redox states, enzyme and transporter fluxes, metabolite concentrations, membrane potential, and respiratory control index under diverse physiological and pathological conditions. The models were also able to quantitatively characterize differential regulations of NADH- and FADH2-linked metabolic pathways, which contribute differently toward regulations of oxidative phosphorylation and ATP synthesis in the heart and kidney cortex and OM mitochondria.
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Affiliation(s)
- Shima Sadri
- Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Xiao Zhang
- Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Said H Audi
- Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Department of Biomedical Engineering, Marquette University, Milwaukee, WI 53223, USA
| | - Allen W Cowley Jr.
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Cardiovascular Research Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Ranjan K Dash
- Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Department of Biomedical Engineering, Marquette University, Milwaukee, WI 53223, USA
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Cardiovascular Research Center, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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Long-Chain and Medium-Chain Fatty Acids in Energy Metabolism of Murine Kidney Mitochondria. Int J Mol Sci 2022; 24:ijms24010379. [PMID: 36613826 PMCID: PMC9820327 DOI: 10.3390/ijms24010379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2022] [Revised: 12/14/2022] [Accepted: 12/20/2022] [Indexed: 12/28/2022] Open
Abstract
Scientists have long established that fatty acids are the primary substrates for kidney mitochondria. However, to date we still do not know how long-chain and middle-chain fatty acids are oxidized at the mitochondrial level. Our previous research has shown that mitochondria from the heart, brain, and kidney oxidize palmitoylcarnitine at a high rate only in the presence of succinate, glutamate, or pyruvate. In this paper, we report properties of the isolated kidney mitochondria and how malate and succinate affect the oxidation of C16 and C8 acylcarnitines. The isolated kidney mitochondria contain very few endogenous substrates and require malate to oxidize pyruvate, glutamate, and C16 or C8 acylcarnitines. We discovered that with 10 µM of C16 or C8 acylcarnitines, low concentrations of malate (0.2 mM) or succinate (0.5 mM) enhance the States 4 and 3 respiratory rates several times. The highest respiration rates were observed with C16 or C8 acylcarnitines and 5 mM succinate mixtures. Results show that kidney mitochondria, unlike the heart and brain mitochondria, lack the intrinsic inhibition of succinate dehydrogenase. Additionally, results show that the oxidation of fatty acid by the small respirasome's supercomplex generates a high level of CoQH2, and this makes SDH in the presence of succinate reverse the flow of electrons from CoQH2 to reduce fumarate to succinate. Finally, we report evidence that succinate dehydrogenase is a key mitochondrial enzyme that allows fast oxidation of fatty acids and turns the TCA cycle function from the catabolic to the anabolic and anaplerotic metabolic pathways.
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JEDLIČKA J, GRUNDMANOVÁ M, ŠVÍGLEROVÁ J, TŮMA Z, NALOS L, RAJDL D, ŠTENGL M, KUNCOVÁ J. Mitochondrial dysfunction in kidney cortex and medulla of subtotally nephrectomized rats. Physiol Res 2022; 71:S219-S226. [PMID: 36647910 PMCID: PMC9906659 DOI: 10.33549/physiolres.935000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Five-sixths nephrectomy is a widely used experimental model of chronic kidney disease (CKD) that is associated with severe mitochondrial dysfunction of the remnant tissue. In this study, we assessed the effect of CKD on mitochondrial respiration separately in the rat kidney cortex and medulla 10 weeks after induction of CKD by subtotal 5/6 nephrectomy (SNX). Mitochondrial oxygen consumption was evaluated on mechanically permeabilized samples of kidney cortex and medulla using high-resolution respirometry and expressed per mg of tissue wet weight or IU citrate synthase (CS) activity. Mitochondrial respiration in the renal cortex of SNX rats was significantly reduced in all measured respiratory states if expressed per unit wet weight and remained lower if recalculated per IU citrate synthase activity, i.e. per mitochondrial mass. In contrast, the profound decrease in the activity of CS in SNX medulla resulted in significantly elevated respiratory states expressing the OXPHOS capacity when Complexes I and II or II only are provided with electrons, LEAK respiration after oligomycin injection, and Complex IV-linked oxygen consumption per unit CS activity suggesting compensatory hypermetabolic state in remaining functional mitochondria that is not sufficient to fully compensate for respiratory deficit expressed per tissue mass. The results document that CKD induced by 5/6 nephrectomy in the rat is likely to cause not only mitochondrial respiratory dysfunction (in the kidney cortex), but also adaptive changes in the medulla that tend to at least partially compensate for mitochondria loss.
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Affiliation(s)
- Jan JEDLIČKA
- Institute of Physiology, Faculty of Medicine in Plzeň, Charles University, Plzeň, Czech Republic
| | - Martina GRUNDMANOVÁ
- Institute of Physiology, Faculty of Medicine in Plzeň, Charles University, Plzeň, Czech Republic
| | - Jitka ŠVÍGLEROVÁ
- Institute of Physiology, Faculty of Medicine in Plzeň, Charles University, Plzeň, Czech Republic,Biomedical Centre, Faculty of Medicine in Plzeň, Charles University, Plzeň, Czech Republic
| | - Zdeněk TŮMA
- Biomedical Centre, Faculty of Medicine in Plzeň, Charles University, Plzeň, Czech Republic
| | - Lukáš NALOS
- Institute of Physiology, Faculty of Medicine in Plzeň, Charles University, Plzeň, Czech Republic
| | - Daniel RAJDL
- Department of Clinical Biochemistry and Hematology, Faculty of Medicine in Plzeň, Charles University, Plzeň, Czech Republic
| | - Milan ŠTENGL
- Institute of Physiology, Faculty of Medicine in Plzeň, Charles University, Plzeň, Czech Republic,Biomedical Centre, Faculty of Medicine in Plzeň, Charles University, Plzeň, Czech Republic
| | - Jitka KUNCOVÁ
- Institute of Physiology, Faculty of Medicine in Plzeň, Charles University, Plzeň, Czech Republic
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Zhang X, Tomar N, Kandel SM, Audi SH, Cowley AW, Dash RK. Substrate- and Calcium-Dependent Differential Regulation of Mitochondrial Oxidative Phosphorylation and Energy Production in the Heart and Kidney. Cells 2021; 11:131. [PMID: 35011693 PMCID: PMC8750792 DOI: 10.3390/cells11010131] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 12/26/2021] [Accepted: 12/28/2021] [Indexed: 11/16/2022] Open
Abstract
Mitochondrial dehydrogenases are differentially stimulated by Ca2+. Ca2+ has also diverse regulatory effects on mitochondrial transporters and other enzymes. However, the consequences of these regulatory effects on mitochondrial oxidative phosphorylation (OxPhos) and ATP production, and the dependencies of these consequences on respiratory substrates, have not been investigated between the kidney and heart despite the fact that kidney energy requirements are second only to those of the heart. Our objective was, therefore, to elucidate these relationships in isolated mitochondria from the kidney outer medulla (OM) and heart. ADP-induced mitochondrial respiration was measured at different CaCl2 concentrations in the presence of various respiratory substrates, including pyruvate + malate (PM), glutamate + malate (GM), alpha-ketoglutarate + malate (AM), palmitoyl-carnitine + malate (PCM), and succinate + rotenone (SUC + ROT). The results showed that, in both heart and OM mitochondria, and for most complex I substrates, Ca2+ effects are biphasic: small increases in Ca2+ concentration stimulated, while large increases inhibited mitochondrial respiration. Furthermore, significant differences in substrate- and Ca2+-dependent O2 utilization towards ATP production between heart and OM mitochondria were observed. With PM and PCM substrates, Ca2+ showed more prominent stimulatory effects in OM than in heart mitochondria, while with GM and AM substrates, Ca2+ had similar biphasic regulatory effects in both OM and heart mitochondria. In contrast, with complex II substrate SUC + ROT, only inhibitory effects on mitochondrial respiration was observed in both the heart and the OM. We conclude that the regulatory effects of Ca2+ on mitochondrial OxPhos and ATP synthesis are biphasic, substrate-dependent, and tissue-specific.
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Affiliation(s)
- Xiao Zhang
- Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI 53226, USA; (X.Z.); (N.T.); (S.M.K.)
| | - Namrata Tomar
- Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI 53226, USA; (X.Z.); (N.T.); (S.M.K.)
| | - Sunil M. Kandel
- Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI 53226, USA; (X.Z.); (N.T.); (S.M.K.)
| | - Said H. Audi
- Department of Biomedical Engineering, Marquette University, Milwaukee, WI 53223, USA;
| | - Allen W. Cowley
- Center of Systems Molecular Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
| | - Ranjan K. Dash
- Department of Biomedical Engineering, Medical College of Wisconsin, Milwaukee, WI 53226, USA; (X.Z.); (N.T.); (S.M.K.)
- Center of Systems Molecular Medicine, Medical College of Wisconsin, Milwaukee, WI 53226, USA
- Department of Physiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA
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