scholarly journals Comparison of some metabolic parameters in the perfused and the incubated rat diaphragm muscle with diaphragm muscle in vivo

1971 ◽  
Vol 125 (1) ◽  
pp. 93-96 ◽  
Author(s):  
K. A. Rookledge
Keyword(s):  
Oxidative Phosphorylation ◽  
Water Content ◽  
Lactate Production ◽  
Metabolic Parameters ◽  
Diaphragm Muscle ◽  
Rat Diaphragm ◽  
Free Glucose ◽  
Hexose Phosphates

1. A method is described for perfusing the rat diaphragm muscle. 2. The following parameters were compared in both perfused and non-perfused incubated preparations: water content, sorbitol space, rate of lactate production, and the concentrations of tissue glucose, pyruvate, lactate, hexose phosphate intermediates, ATP and AMP. No significant differences were found. 3. Significant differences, however, were found on comparison of the tissue kept in vitro with the tissue in vivo. Immediately after removal of the tissue from the animal, the concentrations of the hexose phosphates and ATP were found to be much higher than after incubation or perfusion, and the concentrations of free glucose and of AMP were much lower, possibly indicating that the capacity for oxidative phosphorylation of glucose is impaired in vitro because of hypoxia.

Effect of dichloroacetate on mechanical performance and metabolism of compromised diaphragm muscle

1992 ◽  
Vol 72 (3) ◽  
pp. 1149-1155 ◽  
Author(s):  
B. P. deBoisblanc ◽  
K. Meszaros ◽  
A. Burns ◽  
G. J. Bagby ◽  
S. Nelson ◽  
...  
Keyword(s):  
Glucose Oxidation ◽  
Mechanical Performance ◽  
Lactate Production ◽  
Diaphragm Muscle ◽  
Tetanic Stimulation ◽  
Lactate Oxidation ◽  
Diaphragmatic Fatigue ◽  
Tension Generation

We investigated the effect of dichloroacetate (DCA) on tension generation and carbohydrate metabolism of the rat diaphragm in vitro. Isolated diaphragms were placed in individual organ chambers and were hooked to force-displacement transducers. Net lactate production and glucose and lactate oxidation were measured in vitro. Diaphragmatic fatigue was precipitated by in vivo endotoxemic shock, by in vitro hypoxia, or by in vitro repetitive tetanic stimulation. In diaphragms isolated from endotoxemic rats, DCA increased tension generation by 30 and 20% at stimulation frequencies of 20 and 100 Hz, respectively. Associated with changes in mechanical performance, DCA reduced net lactate production by 53% after 60 min of incubation and increased glucose oxidation 54% but had no effect on lactate oxidation. During in vitro hypoxia, DCA reduced net diaphragmatic lactate production by 30% and increased glucose oxidation by 45% but did not attenuate hypoxic fatigue. DCA had no effect on tension generation during repetitive tetanic stimulation. We conclude that DCA improves in vitro diaphragmatic fatigue due to endotoxicosis but not due to hypoxia or repetitive stimulation.

THE WATER AND ELECTROLYTE METABOLISM OF RAT DIAPHRAGM IN VITRO

1956 ◽  
Vol 34 (1) ◽  
pp. 1069-1083 ◽  
Author(s):  
R. H. Rixon ◽  
J. A. F. Stevenson
Keyword(s):  
Intracellular Water ◽  
Diaphragm Muscle ◽  
Optimal Conditions ◽  
Rat Diaphragm ◽  
Concentration Gradients ◽  
Hypoxic Conditions ◽  
Diaphragm In Vitro ◽  
Sodium And Potassium

The distribution of water and of sodium and potassium between the cell and synthetic environments has been studied in rat diaphragm muscle. It has been found that: (1) the amount of intracellular water is markedly increased at 0 °C. in oxygen and at 37 °C. in nitrogen compared to that of tissue at 37 °C. in oxygen, in media up to 0.75 osmolar; (2) optimal conditions of temperature and oxygen are necessary to prevent or reduce the uptake of water; (3) swelling at reduced temperatures and under hypoxic conditions is related to the oxygen uptake; (4) the loss of tissue solids during incubation does not have any significant effect on the calculation of the total tissue and intracellular water; (5) the concentration of total sodium and potassium in the tissue, in vivo and in vitro at optimal conditions is slightly in excess of that in the plasma water or incubating medium—this is believed not to represent an active hypertonicity; (6) concomitant with the uptake of water there are marked redistributions of sodium and potassium, the gain of sodium being greater than the loss of potassium. It is concluded that the swelling of tissue cells under conditions that inhibit oxidative metabolism is primarily due to the redistribution of electrolytes and that the natural distribution of water in muscle is determined by active maintenance of the concentration gradients of sodium and potassium across the cell membrane.

THE WATER AND ELECTROLYTE METABOLISM OF RAT DIAPHRAGM IN VITRO

1956 ◽  
Vol 34 (5) ◽  
pp. 1069-1083 ◽  
Author(s):  
R. H. Rixon ◽  
J. A. F. Stevenson
Keyword(s):  
Intracellular Water ◽  
Diaphragm Muscle ◽  
Optimal Conditions ◽  
Rat Diaphragm ◽  
Concentration Gradients ◽  
Hypoxic Conditions ◽  
Diaphragm In Vitro ◽  
Sodium And Potassium

The distribution of water and of sodium and potassium between the cell and synthetic environments has been studied in rat diaphragm muscle. It has been found that: (1) the amount of intracellular water is markedly increased at 0 °C. in oxygen and at 37 °C. in nitrogen compared to that of tissue at 37 °C. in oxygen, in media up to 0.75 osmolar; (2) optimal conditions of temperature and oxygen are necessary to prevent or reduce the uptake of water; (3) swelling at reduced temperatures and under hypoxic conditions is related to the oxygen uptake; (4) the loss of tissue solids during incubation does not have any significant effect on the calculation of the total tissue and intracellular water; (5) the concentration of total sodium and potassium in the tissue, in vivo and in vitro at optimal conditions is slightly in excess of that in the plasma water or incubating medium—this is believed not to represent an active hypertonicity; (6) concomitant with the uptake of water there are marked redistributions of sodium and potassium, the gain of sodium being greater than the loss of potassium. It is concluded that the swelling of tissue cells under conditions that inhibit oxidative metabolism is primarily due to the redistribution of electrolytes and that the natural distribution of water in muscle is determined by active maintenance of the concentration gradients of sodium and potassium across the cell membrane.

scholarly journals Lactate secreted by PKM2 upregulation promotes Galectin-9-mediated immunosuppression via inhibiting NF-κB pathway in HNSCC

2021 ◽  
Vol 12 (8) ◽  
Author(s):  
Hanyue Chang ◽  
Qiaoshi Xu ◽  
Jiayi Li ◽  
Mingyu Li ◽  
Zhiyuan Zhang ◽  
...  
Keyword(s):  
Critical Role ◽  
Lactate Production ◽  
Metabolic Reprogramming ◽  
Migration And Invasion ◽  
Histone Deacetylase 3 ◽  
Proliferation And Metastasis ◽  
Immunosuppressive Microenvironment ◽  
Transcriptional Complex

AbstractPyruvate kinase M2 as a key rate-limiting enzyme in glycolysis, it plays a critical role in metabolic reprogramming and carcinogenesis. However, whether PKM2 can promote immunosuppressive microenvironment formation remains unknown in head and neck squamous cell carcinoma (HNSCC). PKM2 expression was detected using immunohistochemical staining. The biological functions of PKM2 were investigated in vitro and in vivo. Lactate production and the expression of Galectin-9, a critical immunosuppression molecule, were detected after PKM2 knockdown and overexpression in HNSCC cells. The mechanism of lactate regulating Galectin-9 expression through NF-κB signaling was explored in vitro. Overexpression of PKM2 correlates with poor prognosis in HNSCC patients. Silencing PKM2 markedly inhibits proliferation and metastasis capacity in vivo and in vitro, and vice versa. The glycolysis and glycolytic capacity are significantly decreased after PKM2 silencing. Lactate secretion induced by PKM2 significantly promotes migration and invasion capacity. Furthermore, a positive correlation between PKM2 and Galectin-9 expression is observed in HNSCC tissues. The induction of Galectin-9 expression by PKM2 can be affected by a lactate transporter inhibitor. Mechanically, lactate impeded the suppressive transcriptional complex formation of NF-κB and histone deacetylase 3 (HDAC3), which released the transcription of Galectin-9 mediated by NF-κB signaling. Our findings demonstrate that lactate produced by PKM2 upregulation promotes tumor progression and Galectin-9-mediated immunosuppression via NF-κB signaling inhibition in HNSCC, which bridges metabolism and immunosuppression. The novel PKM2-lactate-Galectin-9 axis might be a potential therapeutic target in HNSCC.

scholarly journals Let-7a regulates EV secretion and mitochondrial oxidative phosphorylation by targeting SNAP23 in colorectal cancer

2021 ◽  
Vol 40 (1) ◽  
Author(s):  
You Dong Liu ◽  
Xiao Peng Zhuang ◽  
Dong Lan Cai ◽  
Can Cao ◽  
Qi Sheng Gu ◽  
...  
Keyword(s):  
Oxidative Phosphorylation ◽  
Metabolic Reprogramming ◽  
Luciferase Reporter ◽  
Mitochondrial Oxidative Phosphorylation ◽  
In Vivo Assays ◽  
Reporter Assays ◽  
Extracellular Mirna

Abstract Background MicroRNAs (miRNAs) are abundant in tumor-derived extracellular vesicles (EVs) and the functions of extracellular miRNA to recipient cells have been extensively studied with tumorigenesis. However, the role of miRNA in EV secretion from cancer cells remains unknown. Methods qPCR and bioinformatics analysis were applied for determining extracellular let-7a expression from CRC patient serum and cells. Nanosight particle tracking analysis was performed for investigating the effect of let-7a on EV secretion. Luciferase reporter assays was used for identifying targeted genes synaptosome-associated protein 23 (SNAP23). In vitro and in vivo assays were used for exploring the function of let-7a/SNAP23 axis in CRC progression. Bioenergetic assays were performed for investigating the role of let-7a/SNAP23 in cellular metabolic reprogramming. Results let-7a miRNA was elevated in serum EVs from CRC patients and was enriched in CRC cell-derived EVs. We determined that let-7a could suppress EV secretion directly targeting SNAP23. In turn, SNAP23 promotes EV secretion of let-7a to downregulate the intracellular let-7a expression. In addition, we found a novel mechanism of let-7a/SNAP23 axis by regulating mitochondrial oxidative phosphorylation (OXPHOS) through Lin28a/SDHA signaling pathway. Conclusions Let-7a plays an essential role in not only inhibiting EV secretion, but also suppressing OXPHOS through SNAP23, resulting in the suppression of CRC progression, suggesting that let-7a/SNAP23 axis could provide not only effective tumor biomarkers but also novel targets for tumor therapeutic strategies.

scholarly journals IL-32 is a metabolic regulator promoting survival and proliferation of malignant plasma cells

2021 ◽  
Author(s):  
Kristin Roseth Aass ◽  
Robin Mjelle ◽  
Martin H. Kastnes ◽  
Synne S. Tryggestad ◽  
Luca M. van den Brink ◽  
...  
Keyword(s):  
Multiple Myeloma ◽  
Oxidative Phosphorylation ◽  
Plasma Cells ◽  
Inflammatory Diseases ◽  
Mitochondrial Respiratory Chain ◽  
Gene Signature ◽  
Growth And Survival ◽  
Novel Concept

AbstractIL-32 is a non-classical cytokine expressed in cancers, inflammatory diseases and infections. IL-32 can have both extracellular and intracellular functions, and its receptor is not identified. We here demonstrate that endogenously expressed, intracellular IL-32 binds to components of the mitochondrial respiratory chain and promotes oxidative phosphorylation. Knocking out IL-32 in malignant plasma cells significantly reduced survival and proliferation in vitro and in vivo. High throughput transcriptomic and MS-metabolomic profiling of IL-32 KO cells revealed that loss of IL-32 leads to profound perturbations in metabolic pathways, with accumulation of lipids, pyruvate precursors and citrate, indicative of reduced mitochondrial function. IL-32 is expressed in a subgroup of multiple myeloma patients with an inferior prognosis. Primary myeloma cells expressing IL-32 were characterized by a plasma cell gene signature associated with immune activation, proliferation and oxidative phosphorylation. We propose a novel concept for regulation of metabolism by an intracellular cytokine and identify IL-32 as an endogenous growth and survival factor for malignant plasma cells. IL-32 is a potential prognostic biomarker and a treatment target in multiple myeloma.

scholarly journals Proton export drives the Warburg Effect

2021 ◽  
Author(s):  
Shonagh Russell ◽  
Liping Xu ◽  
Yoonseok Kam ◽  
Dominique Abrahams ◽  
Bryce Ordway ◽  
...  
Keyword(s):  
Warburg Effect ◽  
Cancer Metabolism ◽  
Aerobic Glycolysis ◽  
Lactate Production ◽  
Glycolytic Enzymes ◽  
Hek293 Cells ◽  
Driver Mutations ◽  
The Warburg Effect

Aggressive cancers commonly ferment glucose to lactic acid at high rates, even in the presence of oxygen. This is known as aerobic glycolysis, or the “Warburg Effect”. It is widely assumed that this is a consequence of the upregulation of glycolytic enzymes. Oncogenic drivers can increase the expression of most proteins in the glycolytic pathway, including the terminal step of exporting H+ equivalents from the cytoplasm. Proton exporters maintain an alkaline cytoplasmic pH, which can enhance all glycolytic enzyme activities, even in the absence of oncogene-related expression changes. Based on this observation, we hypothesized that increased uptake and fermentative metabolism of glucose could be driven by the expulsion of H+ equivalents from the cell. To test this hypothesis, we stably transfected lowly-glycolytic MCF-7, U2-OS, and glycolytic HEK293 cells to express proton exporting systems: either PMA1 (yeast H+-ATPase) or CAIX (carbonic anhydrase 9). The expression of either exporter in vitro enhanced aerobic glycolysis as measured by glucose consumption, lactate production, and extracellular acidification rate. This resulted in an increased intracellular pH, and metabolomic analyses indicated that this was associated with an increased flux of all glycolytic enzymes upstream of pyruvate kinase. These cells also demonstrated increased migratory and invasive phenotypes in vitro, and these were recapitulated in vivo by more aggressive behavior, whereby the acid-producing cells formed higher grade tumors with higher rates of metastases. Neutralizing tumor acidity with oral buffers reduced the metastatic burden. Therefore, cancer cells with increased H+ export increase intracellular alkalization, even without oncogenic driver mutations, and this is sufficient to alter cancer metabolism towards a Warburg phenotype.

scholarly journals TOP1MT deficiency promotes GC invasion and migration via the enhancements of LDHA expression and aerobic glycolysis

2017 ◽  
Vol 24 (11) ◽  
pp. 565-578 ◽  
Author(s):  
Hongqiang Wang ◽  
Rui Zhou ◽  
Li Sun ◽  
Jianling Xia ◽  
Xuchun Yang ◽  
...  
Keyword(s):  
Cancer Progression ◽  
Topoisomerase I ◽  
Target Genes ◽  
Aerobic Glycolysis ◽  
Lactate Production ◽  
Migration And Invasion ◽  
Glucose Transporter 1 ◽  
Mesenchymal Transition

Aerobic glycolysis plays an important role in cancer progression. New target genes regulating cancer aerobic glycolysis must be explored to improve patient prognosis. Mitochondrial topoisomerase I (TOP1MT) deficiency suppresses glucose oxidative metabolism but enhances glycolysis in normal cells. Here, we examined the role of TOP1MT in gastric cancer (GC) and attempted to determine the underlying mechanism. Using in vitro and in vivo experiments and analyzing the clinicopathological characteristics of patients with GC, we found that TOP1MT expression was lower in GC samples than in adjacent nonmalignant tissues. TOP1MT knockdown significantly promoted GC migration and invasion in vitro and in vivo. Importantly, TOP1MT silencing increased glucose consumption, lactate production, glucose transporter 1 expression and the epithelial-mesenchymal transition (EMT) in GC. Additionally, regulation of glucose metabolism induced by TOP1MT was significantly associated with lactate dehydrogenase A (LDHA) expression. A retrospective analysis of clinical data from 295 patients with GC demonstrated that low TOP1MT expression was associated with lymph node metastasis, recurrence and high mortality rates. TOP1MT deficiency enhanced glucose aerobic glycolysis by stimulating LDHA to promote GC progression.

Theophylline minimally alters contractile properties of canine diaphragm in vitro

1990 ◽  
Vol 69 (4) ◽  
pp. 1390-1396 ◽  
Author(s):  
E. Derom ◽  
S. Janssens ◽  
V. De Bock ◽  
M. Decramer
Keyword(s):  
High Frequency ◽  
Force Production ◽  
Contractile Properties ◽  
Diaphragm Muscle ◽  
Muscle Bundle ◽  
Time To Peak ◽  
Diaphragm In Vitro ◽  
Tetanic Tension

We examined the effects of theophylline on contractile properties and high-frequency fatigue of canine diaphragm in vitro. Eighteen diaphragm muscle bundles were obtained from 10 anesthetized dogs and equilibrated in oxygenated Krebs solution to 100, 200, or 300 mg/l theophylline. These bundles were compared with 18 matched control bundles from the contralateral hemidiaphragm. No statistically significant differences in twitch tension, tetanic tension, twitch-to-tetanus ratio, time to peak tension, or half-relaxation time were observed. Concentrations of 300 mg/l theophylline, however, significantly (P less than 0.05) increased force production at 10 Hz by 32%. A similar tendency was present at lower concentrations and exhibited a clear dose-response behavior. High-frequency fatigue was similar in control and theophylline-treated bundles. We conclude that supratherapeutic in vitro concentrations of theophylline do not increase maximal tetanic tension and do not protect against muscle fatigue but potentiate relative force production at low stimulation frequencies. This relatively small effect cannot be explained by poor diffusion of the drug in the muscle bundle, because theophylline concentrations in the muscle bath and in the muscle bundle were virtually identical. Moreover, it remains unclear whether this potentially beneficial effect can be achieved at in vivo attainable serum concentrations.

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