Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.812
Filtrar
1.
Neuropharmacology ; 257: 110054, 2024 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-38950691

RESUMO

Vasogenic brain edema, a potentially life-threatening consequence following an acute ischemic stroke, is a major clinical problem. This research aims to explore the therapeutic benefits of nimodipine, a calcium channel blocker, in mitigating vasogenic cerebral edema and preserving blood-brain barrier (BBB) function in an ischemic stroke rat model. In this research, animals underwent the induction of ischemic stroke via a 60-min blockage of the middle cerebral artery and treated with a nonhypotensive dose of nimodipine (1 mg/kg/day) for a duration of five days. The wet/dry method was employed to identify cerebral edema, and the Evans blue dye extravasation technique was used to assess the permeability of the BBB. Furthermore, immunofluorescence staining was utilized to assess the protein expression levels of matrix metalloproteinase-9 (MMP-9) and intercellular adhesion molecule-1 (ICAM-1). The study also examined mitochondrial function by evaluating mitochondrial swelling, succinate dehydrogenase (SDH) activity, the collapse of mitochondrial membrane potential (MMP), and the generation of reactive oxygen species (ROS). Post-stroke administration of nimodipine led to a significant decrease in cerebral edema and maintained the integrity of the BBB. The protective effects observed were associated with a reduction in cell apoptosis as well as decreased expression of MMP-9 and ICAM-1. Furthermore, nimodipine was observed to reduce mitochondrial swelling and ROS levels while simultaneously restoring MMP and SDH activity. These results suggest that nimodipine may reduce cerebral edema and BBB breakdown caused by ischemia/reperfusion. This effect is potentially mediated through the reduction of MMP-9 and ICAM-1 levels and the enhancement of mitochondrial function.


Assuntos
Barreira Hematoencefálica , Edema Encefálico , Bloqueadores dos Canais de Cálcio , AVC Isquêmico , Metaloproteinase 9 da Matriz , Nimodipina , Animais , Nimodipina/farmacologia , Edema Encefálico/tratamento farmacológico , Edema Encefálico/etiologia , Edema Encefálico/metabolismo , Barreira Hematoencefálica/efeitos dos fármacos , Barreira Hematoencefálica/metabolismo , Masculino , Ratos , AVC Isquêmico/tratamento farmacológico , AVC Isquêmico/metabolismo , Metaloproteinase 9 da Matriz/metabolismo , Bloqueadores dos Canais de Cálcio/farmacologia , Modelos Animais de Doenças , Espécies Reativas de Oxigênio/metabolismo , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Ratos Sprague-Dawley , Molécula 1 de Adesão Intercelular/metabolismo , Infarto da Artéria Cerebral Média/tratamento farmacológico , Infarto da Artéria Cerebral Média/complicações , Dilatação Mitocondrial/efeitos dos fármacos , Succinato Desidrogenase/metabolismo
2.
Int J Radiat Biol ; 100(7): 1093-1103, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38843455

RESUMO

AIMS: This study proposes to investigate the effects of microwave radiation and its thermal effects, compared to thermal effects alone, on the bioenergetics of mitochondria isolated from mouse liver. METHODS: The main parameters investigated in this study are mitochondrial respiration (coupled states: S3 and S4; uncoupled state), using a high-resolution respirometer, and swelling, using a spectrophotometer. RESULTS: Mitochondria irradiated at 2.45 GHz microwave with doses 0.085, 0.113 and 0.141 kJ/g, presented a decrease in S3 and uncoupled state, but an increase in S4. Conversely, mitochondria thermally treated at 40, 44 and 50 °C presented an increasing in S3 and S4, while uncoupled state was unaltered. Mitochondrial swelling increases as a function of the dose or temperature, indicating membrane damages in both cases. CONCLUSION: Microwave radiation and thermal effect alone indicated different bioenergetics mitochondria response. These results imply that the effects due to microwave in medical treatment are not exclusively due to the increase in temperature, but a combination of electromagnetic and thermal effects.


Assuntos
Metabolismo Energético , Micro-Ondas , Mitocôndrias Hepáticas , Animais , Camundongos , Metabolismo Energético/efeitos da radiação , Mitocôndrias Hepáticas/efeitos da radiação , Mitocôndrias Hepáticas/metabolismo , Masculino , Relação Dose-Resposta à Radiação , Temperatura , Dilatação Mitocondrial/efeitos da radiação , Respiração Celular/efeitos da radiação
3.
Physiol Rep ; 12(10): e16056, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38777811

RESUMO

Permeability transition pore (PTP) opening dissipates ion and electron gradients across the internal mitochondrial membrane (IMM), including excess Ca2+ in the mitochondrial matrix. After opening, immediate PTP closure must follow to prevent outer membrane disruption, loss of cytochrome c, and eventual apoptosis. Flickering, defined as the rapid alternative opening/closing of PTP, has been reported in heart, which undergoes frequent, large variations in Ca2+. In contrast, in tissues that undergo depolarization events less often, such as the liver, PTP would not need to be as dynamic and thus these tissues would not be as resistant to stress. To evaluate this idea, it was decided to follow the reversibility of the permeability transition (PT) in isolated murine mitochondria from two different tissues: the very dynamic heart, and the liver, which suffers depolarizations less frequently. It was observed that in heart mitochondria PT remained reversible for longer periods and at higher Ca2+ loads than in liver mitochondria. In all cases, Ca2+ uptake was inhibited by ruthenium red and PT was delayed by Cyclosporine A. Characterization of this phenomenon included measuring the rate of oxygen consumption, organelle swelling and Ca2+ uptake and retention. Results strongly suggest that there are tissue-specific differences in PTP physiology, as it resists many more Ca2+ additions before opening in a highly active organ such as the heart than in an organ that seldom suffers Ca2+ loading, such as the liver.


Assuntos
Cálcio , Mitocôndrias Cardíacas , Mitocôndrias Hepáticas , Proteínas de Transporte da Membrana Mitocondrial , Poro de Transição de Permeabilidade Mitocondrial , Ratos Wistar , Animais , Poro de Transição de Permeabilidade Mitocondrial/metabolismo , Masculino , Cálcio/metabolismo , Mitocôndrias Cardíacas/metabolismo , Mitocôndrias Hepáticas/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Ratos , Consumo de Oxigênio , Fígado/metabolismo , Dilatação Mitocondrial/efeitos dos fármacos , Ciclosporina/farmacologia
4.
Drug Dev Res ; 85(4): e22199, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38812443

RESUMO

It has been reported that lipophilic statins such as atorvastatin can more readily penetrate into ß-cells and reach the mitochondria, resulting in mitochondrial dysfunction, oxidative stress, decrease in insulin release. Many studies have shown that natural products can protect mitochondrial dysfunction induced by drug in different tissue. We aimed to explore mitochondrial protection potency of hesperidin, vanillic acid, and sinapic acid as natural compounds against mitochondrial dysfunction induced by atorvastatin in pancreas isolated mitochondria. Mitochondria were isolated form rat pancreas and directly treated with toxic concentration of atorvastatin (500 µM) in presence of various concentrations hesperidin, vanillic acid, and sinapic acid (1, 10, and 100 µM) separately. Mitochondrial toxicity parameters such as the reactive oxygen species (ROS) formation, succinate dehydrogenases (SDH) activity, mitochondrial swelling, depletion of glutathione (GSH), mitochondrial membrane potential (MMP) collapse, and malondialdehyde (MDA) production were measured. Our findings demonstrated that atorvastatin directly induced mitochondrial toxicity at concentration of 500 µM and higher in pancreatic mitochondria. Except MDA, atorvastatin caused significantly reduction in SDH activity, mitochondrial swelling, ROS formation, depletion of GSH, and collapse of MMP. While, our data showed that all three protective compounds at low concentrations ameliorated atorvastatin-induced mitochondrial dysfunction with the increase of SDH activity, improvement of mitochondrial swelling, MMP collapse and mitochondrial GSH, and reduction of ROS formation. We can conclude that hesperidin, vanillic acid, and sinapic acid can directly reverse the toxic of atorvastatin in rat pancreas isolated mitochondria, which may be beneficial for protection against diabetogenic-induced mitochondrial dysfunction in pancreatic ß-cells.


Assuntos
Atorvastatina , Ácidos Cumáricos , Hesperidina , Potencial da Membrana Mitocondrial , Mitocôndrias , Dilatação Mitocondrial , Pâncreas , Espécies Reativas de Oxigênio , Ácido Vanílico , Animais , Atorvastatina/farmacologia , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Pâncreas/efeitos dos fármacos , Pâncreas/patologia , Pâncreas/metabolismo , Ácidos Cumáricos/farmacologia , Ratos , Espécies Reativas de Oxigênio/metabolismo , Masculino , Dilatação Mitocondrial/efeitos dos fármacos , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Ácido Vanílico/farmacologia , Hesperidina/farmacologia , Glutationa/metabolismo , Ratos Wistar , Succinato Desidrogenase/metabolismo , Malondialdeído/metabolismo
5.
Circ Res ; 134(10): 1292-1305, 2024 May 10.
Artigo em Inglês | MEDLINE | ID: mdl-38618716

RESUMO

BACKGROUND: During myocardial ischemia/reperfusion (I/R) injury, high levels of matrix Ca2+ and reactive oxygen species (ROS) induce the opening of the mitochondrial permeability transition pore (mPTP), which causes mitochondrial dysfunction and ultimately necrotic death. However, the mechanisms of how these triggers individually or cooperatively open the pore have yet to be determined. METHODS: Here, we use a combination of isolated mitochondrial assays and in vivo I/R surgery in mice. We challenged isolated liver and heart mitochondria with Ca2+, ROS, and Fe2+ to induce mitochondrial swelling. Using inhibitors of the mPTP (cyclosporine A or ADP) lipid peroxidation (ferrostatin-1, MitoQ), we determined how the triggers elicit mitochondrial damage. Additionally, we used the combination of inhibitors during I/R injury in mice to determine if dual inhibition of these pathways is additivity protective. RESULTS: In the absence of Ca2+, we determined that ROS fails to trigger mPTP opening. Instead, high levels of ROS induce mitochondrial dysfunction and rupture independently of the mPTP through lipid peroxidation. As expected, Ca2+ in the absence of ROS induces mPTP-dependent mitochondrial swelling. Subtoxic levels of ROS and Ca2+ synergize to induce mPTP opening. Furthermore, this synergistic form of Ca2+- and ROS-induced mPTP opening persists in the absence of CypD (cyclophilin D), suggesting the existence of a CypD-independent mechanism for ROS sensitization of the mPTP. These ex vivo findings suggest that mitochondrial dysfunction may be achieved by multiple means during I/R injury. We determined that dual inhibition of the mPTP and lipid peroxidation is significantly more protective against I/R injury than individually targeting either pathway alone. CONCLUSIONS: In the present study, we have investigated the relationship between Ca2+ and ROS, and how they individually or synergistically induce mitochondrial swelling. Our findings suggest that Ca2+ mediates mitochondrial damage through the opening of the mPTP, although ROS mediates its damaging effects through lipid peroxidation. However, subtoxic levels both Ca2+ and ROS can induce mPTP-mediated mitochondrial damage. Targeting both of these triggers to preserve mitochondria viability unveils a highly effective therapeutic approach for mitigating I/R injury.


Assuntos
Peroxidação de Lipídeos , Camundongos Endogâmicos C57BL , Mitocôndrias Cardíacas , Mitocôndrias Hepáticas , Proteínas de Transporte da Membrana Mitocondrial , Poro de Transição de Permeabilidade Mitocondrial , Traumatismo por Reperfusão Miocárdica , Espécies Reativas de Oxigênio , Animais , Peroxidação de Lipídeos/efeitos dos fármacos , Poro de Transição de Permeabilidade Mitocondrial/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Camundongos , Mitocôndrias Cardíacas/metabolismo , Mitocôndrias Cardíacas/efeitos dos fármacos , Mitocôndrias Cardíacas/patologia , Masculino , Traumatismo por Reperfusão Miocárdica/metabolismo , Traumatismo por Reperfusão Miocárdica/prevenção & controle , Traumatismo por Reperfusão Miocárdica/patologia , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Mitocôndrias Hepáticas/metabolismo , Mitocôndrias Hepáticas/patologia , Mitocôndrias Hepáticas/efeitos dos fármacos , Cálcio/metabolismo , Dilatação Mitocondrial/efeitos dos fármacos
6.
Basic Res Cardiol ; 118(1): 39, 2023 09 29.
Artigo em Inglês | MEDLINE | ID: mdl-37775647

RESUMO

Giant mitochondria are frequently observed in different disease models within the brain, kidney, and liver. In cardiac muscle, these enlarged organelles are present across diverse physiological and pathophysiological conditions including in ageing and exercise, and clinically in alcohol-induced heart disease and various cardiomyopathies. This mitochondrial aberration is widely considered an early structural hallmark of disease leading to adverse organ function. In this thematic paper, we discuss the current state-of-knowledge on the presence, structure and functional implications of giant mitochondria in heart muscle. Despite its demonstrated reoccurrence in different heart diseases, the literature on this pathophysiological phenomenon remains relatively sparse since its initial observations in the early 60s. We review historical and contemporary investigations from cultured cardiomyocytes to human tissue samples to address the role of giant mitochondria in cardiac health and disease. Finally, we discuss their significance for the future development of novel mitochondria-targeted therapies to improve cardiac metabolism and functionality.


Assuntos
Cardiomiopatias , Miócitos Cardíacos , Humanos , Miócitos Cardíacos/metabolismo , Dilatação Mitocondrial , Mitocôndrias/metabolismo , Miocárdio/metabolismo , Mitocôndrias Cardíacas/metabolismo
7.
Liver Int ; 43(11): 2365-2378, 2023 11.
Artigo em Inglês | MEDLINE | ID: mdl-37615254

RESUMO

This thematic review aims to provide an overview of the current state of knowledge about the occurrence of giant mitochondria or megamitochondria in liver parenchymal cells. Their presence and accumulation are considered to be a major pathological hallmark of the health and fate of liver parenchymal cells that leads to overall tissue deterioration and eventually results in organ failure. The first description on giant mitochondria dates back to the 1960s, coinciding with the availability of the first generation of electron microscopes in clinical diagnostic laboratories. Detailed accounts on their ultrastructure have mostly been described in patients suffering from alcoholic liver disease, chronic hepatitis, hepatocellular carcinoma and non-alcoholic fatty liver disease. Interestingly, from this extensive literature survey, it became apparent that giant mitochondria or megamitochondria present themselves with or without highly organised crystal-like intramitochondrial inclusions. The origin, formation and potential role of giant mitochondria remain to-date largely unanswered. Likewise, the biochemical composition of the well-organised crystal-like inclusions and their possible impact on mitochondrial function is unclear. Herein, concepts about the possible mechanism of their formation and three-dimensional architecture will be approached. We will furthermore discuss their importance in diagnostics, including future research outlooks and potential therapeutic interventions to cure liver disease where giant mitochondria are implemented.


Assuntos
Hepatopatias Alcoólicas , Hepatopatia Gordurosa não Alcoólica , Humanos , Dilatação Mitocondrial , Mitocôndrias Hepáticas/patologia , Hepatopatias Alcoólicas/patologia , Hepatopatia Gordurosa não Alcoólica/patologia , Hepatite Crônica/patologia , Fígado/patologia
8.
Toxicon ; 233: 107259, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37595687

RESUMO

Immune system hyperactivation is involved with clinical severity and pathological alterations during scorpion envenomation. In a murine model, mice inoculated with a lethal dose of Tityus serrulatus scorpion venom presented mitochondrial swelling in cardiomyocytes, with other structures such as sarcomeres and intercalated disks preserved. Treatment with dexamethasone or knockout animals to the interleukin-1ß receptor do not undergo mitochondrial changes in cardiomyocytes during envenomation.


Assuntos
Picadas de Escorpião , Venenos de Escorpião , Animais , Camundongos , Miócitos Cardíacos , Dilatação Mitocondrial , Modelos Animais de Doenças , Venenos de Escorpião/toxicidade , Escorpiões
11.
Mitochondrion ; 71: 64-75, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37276954

RESUMO

As the cell's energy factory and metabolic hub, mitochondria are critical for ATP synthesis to maintain cellular function. Mitochondria are highly dynamic organelles that continuously undergo fusion and fission to alter their size, shape, and position, with mitochondrial fusion and fission being interdependent to maintain the balance of mitochondrial morphological changes. However, in response to metabolic and functional damage, mitochondria can grow in size, resulting in a form of abnormal mitochondrial morphology known as megamitochondria. Megamitochondria are characterized by their considerably larger size, pale matrix, and marginal cristae structure and have been observed in various human diseases. In energy-intensive cells like hepatocytes or cardiomyocytes, the pathological process can lead to the growth of megamitochondria, which can further cause metabolic disorders, cell damage and aggravates the progression of the disease. Nonetheless, megamitochondria can also form in response to short-term environmental stimulation as a compensatory mechanism to support cell survival. However, extended stimulation can reverse the benefits of megamitochondria leading to adverse effects. In this review, we will focus on the findings of the different roles of megamitochondria, and their link to disease development to identify promising clinical therapeutic targets.


Assuntos
Doenças Metabólicas , Mitocôndrias , Humanos , Dilatação Mitocondrial , Mitocôndrias/metabolismo , Hepatócitos/metabolismo , Membranas Mitocondriais/metabolismo , Dinâmica Mitocondrial
12.
Hepatology ; 77(1): 159-175, 2023 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-35698731

RESUMO

BACKGROUND AND AIMS: Increased megamitochondria formation and impaired mitophagy in hepatocytes have been linked to the pathogenesis of alcohol-associated liver disease (ALD). This study aims to determine the mechanisms by which alcohol consumption increases megamitochondria formation in the pathogenesis of ALD. APPROACH AND RESULTS: Human alcoholic hepatitis (AH) liver samples were used for electron microscopy, histology, and biochemical analysis. Liver-specific dynamin-related protein 1 (DRP1; gene name DNM1L, an essential gene regulating mitochondria fission ) knockout (L-DRP1 KO) mice and wild-type mice were subjected to chronic plus binge alcohol feeding. Both human AH and alcohol-fed mice had decreased hepatic DRP1 with increased accumulation of hepatic megamitochondria. Mechanistic studies revealed that alcohol feeding decreased DRP1 by impairing transcription factor EB-mediated induction of DNM1L . L-DRP1 KO mice had increased megamitochondria and decreased mitophagy with increased liver injury and inflammation, which were further exacerbated by alcohol feeding. Seahorse flux and unbiased metabolomics analysis showed alcohol intake increased mitochondria oxygen consumption and hepatic nicotinamide adenine dinucleotide (NAD + ), acylcarnitine, and ketone levels, which were attenuated in L-DRP1 KO mice, suggesting that loss of hepatic DRP1 leads to maladaptation to alcohol-induced metabolic stress. RNA-sequencing and real-time quantitative PCR analysis revealed increased gene expression of the cGAS-stimulator of interferon genes (STING)-interferon pathway in L-DRP1 KO mice regardless of alcohol feeding. Alcohol-fed L-DRP1 KO mice had increased cytosolic mtDNA and mitochondrial dysfunction leading to increased activation of cGAS-STING-interferon signaling pathways and liver injury. CONCLUSION: Alcohol consumption decreases hepatic DRP1 resulting in increased megamitochondria and mitochondrial maladaptation that promotes AH by mitochondria-mediated inflammation and cell injury.


Assuntos
Hepatite Alcoólica , Hepatopatias Alcoólicas , Camundongos , Humanos , Animais , Dilatação Mitocondrial , Hepatopatias Alcoólicas/metabolismo , Mitocôndrias/metabolismo , Etanol/toxicidade , Nucleotidiltransferases , Inflamação , Interferons , Dinâmica Mitocondrial
13.
Cell Biol Toxicol ; 39(2): 435-450, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-35606662

RESUMO

Mitochondrial metabolism and function are modulated by changes in matrix Ca2+. Small increases in the matrix Ca2+ stimulate mitochondrial bioenergetics, whereas excessive Ca2+ leads to cell death by causing massive matrix swelling and impairing the structural and functional integrity of mitochondria. Sustained opening of the non-selective mitochondrial permeability transition pores (PTP) is the main mechanism responsible for mitochondrial Ca2+ overload that leads to mitochondrial dysfunction and cell death. Recent studies suggest the existence of two or more types of PTP, and adenine nucleotide translocator (ANT) and FOF1-ATP synthase were proposed to form the PTP independent of each other. Here, we elucidated the role of ANT in PTP opening by applying both experimental and computational approaches. We first developed and corroborated a detailed model of the ANT transport mechanism including the matrix (ANTM), cytosolic (ANTC), and pore (ANTP) states of the transporter. Then, the ANT model was incorporated into a simple, yet effective, empirical model of mitochondrial bioenergetics to ascertain the point when Ca2+ overload initiates PTP opening via an ANT switch-like mechanism activated by matrix Ca2+ and is inhibited by extra-mitochondrial ADP. We found that encoding a heterogeneous Ca2+ response of at least three types of PTPs, weakly, moderately, and strongly sensitive to Ca2+, enabled the model to simulate Ca2+ release dynamics observed after large boluses were administered to a population of energized cardiac mitochondria. Thus, this study demonstrates the potential role of ANT in PTP gating and proposes a novel mechanism governing the cryptic nature of the PTP phenomenon.


Assuntos
Nucleotídeos de Adenina , Proteínas de Transporte da Membrana Mitocondrial , Nucleotídeos de Adenina/metabolismo , Dilatação Mitocondrial , Mitocôndrias/metabolismo , Poro de Transição de Permeabilidade Mitocondrial/metabolismo , Cálcio/metabolismo
14.
Methods Mol Biol ; 2497: 129-140, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35771440

RESUMO

The loss of mitochondrial cristae integrity and mitochondrial swelling are hallmarks of multiple forms of necrotic cell death. One of the most well-studied and relevant inducers of mitochondrial swelling is matrix calcium (Ca2+). Respiring mitochondria will intake available Ca2+ into their matrix until a threshold is reached which triggers the opening of the mitochondrial permeability transition pore (MPTP). Upon opening of the pore, mitochondrial membrane potential dissipates and the mitochondria begin to swell, rendering them dysfunctional. The total amount of Ca2+ taken up by a mitochondrion prior to the engagement of the MPTP is referred to as mitochondrial Ca2+ retention capacity (CRC). The CRC/swelling assay is a useful tool for observing the dose-dependent event of mitochondrial dysfunction in real-time. In this technique, isolated mitochondria are treated with specific boluses of Ca2+ until they reach CRC and undergo swelling. A fluorometer is utilized to detect an increase in transmitted light passing through the sample as the mitochondria lose cristae density, and simultaneously measures calcium uptake by way of a Ca2+-specific membrane impermeable fluorescent dye. Here we provide a detailed protocol describing the mitochondrial CRC/swelling assay and we discuss how varying amounts of mitochondria and Ca2+ added to the system affect the dose-dependency of the assay. We also report how to validate the assay by using MPTP and calcium uptake inhibitors and troubleshooting common mistakes that occur with this approach.


Assuntos
Cálcio , Proteínas de Transporte da Membrana Mitocondrial , Cálcio/metabolismo , Mitocôndrias/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Poro de Transição de Permeabilidade Mitocondrial , Dilatação Mitocondrial , Permeabilidade
15.
Prog Biophys Mol Biol ; 172: 15-23, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35447196

RESUMO

Existing theoretical approaches were considered that allow modelling of mitochondrial swelling (MS) dynamics. Simple phenomenological kinetic models were reviewed. Simple and extended biophysical and bioenergetic models that ignore mechanical properties of inner mitochondrial membrane (IMM), and similar models that include these mechanical properties were also reviewed. Limitations of these models we considered, as regards correct modelling of MS dynamics. It was found that simple phenomenological kinetic models have significant limitations, due to dependence of the kinetic parameter values estimated by fitting of the experimental data on the experimental conditions. Additionally, such simple models provide no understanding of the detailed mechanisms behind the MS dynamics, nor of the dynamics of various system parameters during MS. Thus, biophysical and bioenergetic models ignoring IMM mechanical properties can't be used to model the transition between reversible and irreversible MS. However, simple and extended biophysical models that include IMM mechanical properties allow modelling the transition to irreversible swelling. These latter models are still limited due to significantly simplified description of biochemistry, compared to those of bioenergetic models. Finally, a strategy of model development is proposed, towards correct interpretation of the mitochondrial life cycle, including the effects of MS dynamics.


Assuntos
Mitocôndrias , Membranas Mitocondriais , Metabolismo Energético , Cinética , Mitocôndrias/metabolismo , Membranas Mitocondriais/metabolismo , Dilatação Mitocondrial
16.
Biosystems ; 217: 104679, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35413385

RESUMO

Theoretical biophysical model is reported for mitochondrial swelling (MS) dynamics in vivo. This newly developed model is based on the detailed biophysical model of MS dynamics in vitro, where mechanical properties of the inner mitochondrial membrane (IMM) were taken into account. The present model of MS dynamics in vivo is capable of analyzing MS dynamic transition from the reversible (physiological) to the irreversible (pathological) mode. This model was used to describe myocytes, assuming 1000 mitochondria distributed homogeneously over the sarcoplasm. Solute transport through the myocyte membrane was described by simplified phenomenological mechanisms of solute uptake and release. Biophysical processes occurring in mitochondria within cells were similar to those included in the earlier reported in vitro biophysical model of MS dynamics. Additionally, in vivo MS dynamics was simulated in different initial conditions, with results different from those of the in vitro model. Note that the presently reported model is the first attempt to develop a detailed biophysical model for the analysis of MS dynamics in vivo, capable of reproducing the transition between reversible and irreversible MS dynamics.


Assuntos
Mitocôndrias , Membranas Mitocondriais , Fenômenos Biofísicos , Mitocôndrias/fisiologia , Membranas Mitocondriais/metabolismo , Dilatação Mitocondrial/fisiologia
18.
Toxicol Mech Methods ; 32(2): 106-113, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-34431445

RESUMO

Mitochondria have the main roles in myocardial tissue homeostasis, through providing ATP for the vital enzymes in intermediate metabolism, contractile apparatus and maintaining ion homeostasis. Mitochondria-related cardiotoxicity results from the exposure with illicit drugs have previously reported. These illicit drugs interference with processes of normal mitochondrial homeostasis and lead to mitochondrial dysfunction and mitochondrial-related oxidative stress. Cannabis consumption has been shown to cause ventricular tachycardia, to increase the risk of myocardial infarction (MI) and potentially sudden death. Here, we investigated this hypothesis that delta-9-tetrahydrocannabinol (Delta-9-THC) as a main cannabinoid found in cannabis could directly cause mitochondrial dysfunction. Cardiac mitochondria were isolated with mechanical lysis and differential centrifugation form rat heart. The isolated cardiac mitochondria were treated with different concentrations of THC (1, 5, 10, 50, 100 and 500 µM) for 1 hour at 37 °C. Then, succinate dehydrogenase (SDH) activity, mitochondrial swelling, reactive oxygen species (ROS) formation, mitochondrial membrane potential (MMP) collapse and lipid peroxidation were measured in the treated and nontreated isolated cardiac mitochondria. Our observation showed that THC did not cause a deleterious alteration in mitochondrial functions, ROS production, MMP collapse, mitochondrial swelling, oxidative stress and lipid peroxidation in used concentrations (5-100 µM), even in several tests, toxicity showed a decreasing trend. Altogether, the results of the current study showed that THC is not directly toxic in isolated cardiac mitochondria, and even may be helpful in reducing mitochondrial toxicity.


Assuntos
Dronabinol , Mitocôndrias Cardíacas , Animais , Dronabinol/metabolismo , Dronabinol/toxicidade , Potencial da Membrana Mitocondrial , Mitocôndrias Cardíacas/metabolismo , Dilatação Mitocondrial , Estresse Oxidativo , Ratos , Espécies Reativas de Oxigênio/metabolismo
19.
Biosystems ; 210: 104559, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34627969

RESUMO

An extended biophysical model was obtained by upgrading the previously reported one (Khmelinskii and Makarov, 2021). The upgraded model accommodates variations of solute transport rates through the inner mitochondrial membrane (IMM) within the mitochondrial population, described by a Gaussian distribution. However, the model may be used for any functional form of the distribution. The dynamics of system parameters as predicted by the current model differed from that predicted by the previous model in the same initial conditions (Khmelinskii and Makarov, 2021). The amount of change varied from one parameter to the other, remaining in the 1-38% range. The upgraded model fitted the available experimental data with a better accuracy (R = 0.993) compared to the previous model (R = 0.978) using the same experimental data (Khmelinskii and Makarov, 2021). The fitting procedure also estimated the Gaussian distribution parameters. The new model requires much larger computational resources, but given its higher accuracy, it may be used for better analysis of experimental data and for better prediction of MS dynamics in different initial conditions. Note that activities of individual mitochondria in mitochondrial populations should vary within biological tissues. Thus, the currently upgraded model is a better tool for biological and bio-medical applications. We believe that this model is much better adapted to the analysis of MS dynamics in vivo.


Assuntos
Fenômenos Biofísicos/fisiologia , Mitocôndrias/fisiologia , Dilatação Mitocondrial/fisiologia , Modelos Biológicos , Animais , Humanos , Membranas Mitocondriais/fisiologia
20.
Biophys Chem ; 278: 106668, 2021 11.
Artigo em Inglês | MEDLINE | ID: mdl-34418677

RESUMO

Mitochondrial activity as regards ATP production strongly depends on mitochondrial swelling (MS) mode. Therefore, this work analyzes reversible and irreversible MS using a detailed biophysical model. The reported model includes mechanical properties of the inner mitochondrial membrane (IMM). The model describes MS dynamics for spherically symmetric, axisymmetric ellipsoidal and general ellipsoidal mitochondria. Mechanical stretching properties of the IMM were described by a second-rank rigidity tensor. The tensor components were estimated by fitting to the earlier reported results of in vitro experiments. The IMM rigidity constant of ca. 0.008 dyn/nm was obtained for linear deformations. The model also included membrane bending effects, which were small compared to those of membrane stretching. The model was also tested by simulation of the earlier reported experimental data and of the system dynamics at different initial conditions, predicting the system behavior. The transition criteria from reversible to irreversible swelling were determined and tested. The presently developed model is applicable directly to the analysis of in vitro experimental data, while additional improvements are necessary before it could be used to describe mitochondrial swelling in vivo. The reported theoretical model also provides an idea of physically consistent mechanism for the permeability transport pore (PTP) opening, which depends on the IMM stretching stress. In the current study, this idea is discussed briefly, but a detailed theoretical analysis of these ideas will be performed later. The currently developed model provides new understanding of the detailed MS mechanism and of the conditions for the transition between reversible and irreversible MS modes. On the other hand, the current model provides useful mathematical tools, that may be successfully used in mitochondrial biophysics research, and also in other applications, predicting the behavior of mitochondria in different conditions of the surrounding media in vitro or cellular cyto(sarco)plasm in vivo. These mathematical tools are based on real biophysical processes occurring in mitochondria. Thus, we note a significant progress in the theoretical approach, which may be used in real biological systems, compared to the earlier reported models. Significance of this study derives from inclusion of IMM mechanical properties, which directly impact the reversible and irreversible mitochondrial swelling dynamics. Reversible swelling corresponds to reversible IMM deformations, while irreversible swelling corresponds to irreversible deformations, with eventual membrane disruption. The IMM mechanical properties are directly dependent on the membrane biochemical composition and structure. The IMM deformationas are induced by osmotic pressure created by the ionic/neutral solute imbalance between the mitochondrial matrix media and the bulk solution in vitro, or cyto(sarco)plasm in vivo. The novelty of the reported model is in the biophysical mechanism detailing ionic and neutral solute transport for a large number of solutes, which were not taken into account in the earlier reported biophysical models of MS. Therefore, the reported model allows understanding response of mitochondria to the changes of initial concentration(s) of any of the solute(s) included in the model. Note that the values of all of the model parameters and kinetic constants have been estimated and the resulting complete model may be used for quantitative analysis of mitochondrial swelling dynamics in conditions of real in vitro experiments.


Assuntos
Mitocôndrias , Membranas Mitocondriais , Fenômenos Biofísicos , Cálcio/metabolismo , Simulação por Computador , Membranas Mitocondriais/metabolismo , Dilatação Mitocondrial/fisiologia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA