Metabolic inhibitors: effects on metabolism and transport in the proximal tubule

1982 ◽  
Vol 243 (2) ◽  
pp. F133-F140 ◽  
Author(s):  
S. R. Gullans ◽  
P. C. Brazy ◽  
S. P. Soltoff ◽  
V. W. Dennis ◽  
L. J. Mandel
Keyword(s):  
Oxidative Metabolism ◽  
Metabolic Inhibitors ◽  
Antimycin A ◽  
Atp Content ◽  
Atp Production ◽  
Sodium Dependent ◽  
Dependent Transport ◽  
Convoluted Tubules ◽  
Mitochondrial Oxidative Metabolism ◽  
Made In

This study examined the effects of the metabolic inhibitors rotenone and antimycin A on oxidative metabolism and transport in the proximal renal tubule of the rabbit. Measurements of oxygen consumption rate (QO2), cellular ATP content, and mitochondrial NAD redox state were made in suspensions of renal cortical tubules. Parallel experiments were conducted in isolated perfused proximal convoluted tubules to measure the absorption rates of fluid (Jv), phosphate (JlbPO4), and glucose (JlbGlc). The results indicate that rotenone and antimycin A, at doses (10(-6) M) that maximally inhibited mitochondrial oxidative phosphorylation, abolished net fluid and phosphate absorption and nearly eliminated net glucose transport. Partial inhibition of oxidative metabolism with 10(-7) M rotenone caused proportional reductions in QO2, ATP content, and Jv; however, JlbPO4 was reduced more markedly than either Jv or JlbGlc. We conclude that rotenone and antimycin A inhibit the sodium-dependent transport of fluid, phosphate, and glucose by blocking mitochondrial ATP production. Furthermore, the inhibition of mitochondrial oxidative metabolism and the inhibition of net sodium transport are closely correlated.

Differential effects of respiratory inhibitors on glycolysis in proximal tubules

1990 ◽  
Vol 258 (6) ◽  
pp. F1608-F1615 ◽  
Author(s):  
K. G. Dickman ◽  
L. J. Mandel
Keyword(s):  
Oxidative Metabolism ◽  
Cell Injury ◽  
Lactate Production ◽  
Proximal Tubules ◽  
Antimycin A ◽  
Transport Function ◽  
Atp Production ◽  
Rotenone Treatment ◽  
Glycolytic Atp ◽  
Ldh Release

The effects of inhibition of mitochondrial energy production at various points along the respiratory chain on glycolytic lactate production and transport function were examined in a suspension of purified rabbit renal proximal tubules. Paradoxically, partial blockage at site 3 by hypoxia (1% O2) induced lactate production, whereas total site 3 blockage by anoxia (0% O2) failed to stimulate glycolysis. Compared with anoxia, hypoxic tubules exhibited greater preservation of ATP and K+ contents during O2 deprivation and more fully recovered oxidative metabolism and transport function during reoxygenation. The mitochondrial site 1 inhibitor rotenone and the uncoupler carbonyl cyanide-p-trifluorome-thoxyphenylhydrazone (FCCP) were equipotent stimuli for lactate production, whereas the site 2 inhibitor antimycin A failed to stimulate glycolysis despite a 90% inhibition of O2 consumption. Compared with antimycin A, treatment with rotenone or FCCP resulted in less cell injury [measured by lactate dehydrogenase (LDH) release] and greater preservation of cell K+ and ATP contents. 2-Deoxyglucose blocked lactate production by 50% in the presence of rotenone and increased LDH release, suggesting that glycolytic ATP is partially protective. Addition of ouabain during rotenone treatment reduced lactate production by 50%, indicating that glycolytic ATP can be used to fuel the Na pump when mitochondrial ATP production is inhibited. We conclude that 1) proximal tubules can generate lactate during inhibition of oxidative metabolism by hypoxia, rotenone, or FCCP; 2) mitochondrial inhibition is not obligatorily linked to activation of glycolysis, since neither anoxia nor antimycin A stimulate lactate production; 3) when ATP can be produced through anaerobic glycolysis it serves to protect cell viability and transport function during respiratory inhibition.

Effects of Antimycin A and 2-Deoxyglucose on Energy Metabolism in Washed Human Platelets

1979 ◽  
Vol 42 (05) ◽  
pp. 1460-1472 ◽  
Author(s):  
Holm Holmsen ◽  
Linda M Robkin
Keyword(s):  
Plasma Proteins ◽  
Platelet Rich Plasma ◽  
Energy Charge ◽  
Lactate Production ◽  
Human Platelets ◽  
Metabolic Inhibitors ◽  
Antimycin A ◽  
Adenylate Energy Charge ◽  
Atp Production ◽  
Major Mechanism

Summary(1) Human platelets were incubated with [14C]adenine in plasma, washed and resuspended in salt solutions. The effects of incubating the cells with antimycin A and 2- deoxyglucose on the radioactivity of ATP, ADP, AMP, IMP and inosine + hypoxanthine, the total level of ADP and ATP and lactate production were studied. The metabolic inhibitors only affected the cytoplasmic, [14C]-labelled nucleotides, and were apparently without effect on the granular, non-labelled ATP and ADP. (2) Antimycin A caused a rapid, shortlasting decrease in [14C]ATP which was independent on glucose and enhanced by 2- deoxyglucose. Lactate production increased about 3-fold with and without 2-deoxyglucose. The initial fall in [14C]ATP was therefore thought to be due to a failure to immediately substitute for the lost oxidative ATP production. (3) After the initial fall in [14C]ATP no changes took place when glucose was present, while [14C]ATP and the adenylate energy charge decreased when glucose was absent and more so when 2-deoxyglucose was present. Thus, glycogenolysis, corresponding to an ATP turnover of 29.8 nmoles × min-1 × mg-1 protein did not maintain ATP homeostasis in platelets. (4) The changes in [14C]ATP, adenylate energy charge and lactate production under the various conditions strongly suggested that regulation of ATP consumption in the cells was a major mechanism to maintain ATP homeostasis. (5) The changes in the [14C]nucleotides in washed platelets were qualitatively similar to those previously described in platelet-rich plasma (Holmsen et al. 1974); quantitative differences were apparent and found to be due to binding of antimycin A to plasma proteins and counteraction of the effects of 2-deoxyglucose by plasma glucose. In particular, the rapid, initial fall in [14C]ATP occurred only with washed cells and clearly demonstrated a conversion of ATP to hypoxanthine ADP, AMP, IMP and inosine. (6) The cellular AMP deaminase reaction was found not to be related by the adenylate energy charge, in contrast to studies with semipurified enzyme (Chapman & Atkinson 1973). Our results suggested that AMP deamination occurred when [AMP] rose from its resting value of 0.07 mM and was inhibited when [ATP] fell below 2 mM within the cell.

scholarly journals Effects of antimycin A and 2-deoxyglucose on secretion in human platelets. Differential inhibition of the secretion of acid hydrolases and adenine nucleotides

1979 ◽  
Vol 182 (2) ◽  
pp. 413-419 ◽  
Author(s):  
Holm Holmsen ◽  
Linda Robkin ◽  
H. James Day
Keyword(s):  
Shape Change ◽  
Adenine Nucleotides ◽  
Human Platelets ◽  
Dense Granule ◽  
Metabolic Inhibitors ◽  
Antimycin A ◽  
Acid Hydrolase ◽  
Acid Hydrolases ◽  
Dense Granule Secretion ◽  
Granule Secretion

1. Shape change, aggregation and secretion of dense-granule constituents in platelets differ in their dependence on cellular energy metabolism. The possibility that such a difference also exists between secretion of dense-granule constituents and acid hydrolases was investigated. 2. Human platelets were incubated with [14C]adenine in plasma, and then washed and resuspended in salt solutions. The effects of incubating the cells with antimycin A and 2-deoxyglucose on the concentrations of [14C]ATP, ADP, AMP, IMP and inosine plus hypoxanthine and on thrombin-induced secretion of ATP plus ADP and acid hydrolases were studied. The metabolic inhibitors only affected 14C-labelled nucleotides, whereas thrombin only liberated unlabelled ATP and ADP. 3. The extent of secretion decreased progressively with time during incubation with the metabolic inhibitors. At any time the secretion of acid hydrolases, β-N-acetylglucosaminidase, β-glucuronidase and β-galactosidase was inhibited to a greater extent than secretion of ATP plus ADP (dense-granule secretion). 4. Incubation with the metabolic inhibitors shifted the log (dose)–response relationship to higher thrombin concentrations, and with a greater shift for acid hydrolase secretion than for dense-granule secretion. 5. Antimycin, when present alone, caused a marked decrease in the rate of acid hydrolase secretion, but had no effect on dense-granule secretion. 6. These results further support the view that acid hydrolase secretion and dense-granule secretion are separate processes with different requirements for ATP energy. Acid hydrolase secretion, but not dense-granule secretion, appears to depend on a simultaneous rapid generation of ATP, which can be accomplished by oxidative, but not by glycolytic, ATP production.

Gender dimorphism in rat liver mitochondrial oxidative metabolism and biogenesis

2005 ◽  
Vol 289 (2) ◽  
pp. C372-C378 ◽  
Author(s):  
Roberto Justo ◽  
Jordi Boada ◽  
Margalida Frontera ◽  
Jordi Oliver ◽  
Jordi Bermúdez ◽  
...  
Keyword(s):  
Gender Differences ◽  
Protein Content ◽  
Rat Liver ◽  
Oxidative Metabolism ◽  
Mitochondrial Protein ◽  
Electron Microscopic ◽  
Gender Dimorphism ◽  
Protein Levels ◽  
Mitochondrial Fractions ◽  
Mitochondrial Oxidative Metabolism

In the present study, we have investigated gender differences in rat liver mitochondrial oxidative metabolism. Total mitochondrial population (M) as well as the heavy (M1), medium (M3), and light (M8) mitochondrial fractions obtained by means of differential centrifugation steps at 1,000, 3,000, and 8,000 g, respectively, were isolated. Electron microscopic analysis was performed and mitochondrial protein content and cardiolipin levels, mitochondrial O2 flux, ATP synthase activity, mitochondrial membrane potential, and mitochondrial transcription factor A (TFAM) protein levels were measured in each sample. Our results indicate that mitochondria from females have higher protein content and higher cardiolipin levels, greater respiratory and phosphorylative capacities, and more-energized mitochondria in respiratory state 3. Moreover, protein levels of TFAM were four times greater in females than in males. Gender differences in the aforementioned parameters were more patent in the isolated heavy M1 and M3 mitochondrial fractions. The present study demonstrates that gender-related differences in liver mitochondrial function are due mainly to a higher capacity and efficiency of substrate oxidation, likely related to greater mitochondrial machinery in females than in males, which is in accord with greater mitochondrial differentiation in females.

The energy requirement for sodium extrusion from a frog muscle

1954 ◽  
Vol 142 (908) ◽  
pp. 383-392 ◽  
Keyword(s):  
Oxygen Consumption ◽  
Energy Production ◽  
Energy Requirement ◽  
Metabolic Inhibitors ◽  
Sodium Efflux ◽  
External Potassium ◽  
Radioactive Sodium ◽  
Sodium Extrusion ◽  
Frog Sartorius ◽  
Made In

Parallel measurements have been made of the oxygen consumption and efflux of radioactive sodium in pairs of frog sartorius muscles. Calculation of the amount of secretory work necessary for an active extrusion of sodium at the observed rate showed that it would involve the utilization of about one-tenth of the energy available from resting metabolism.This figure may reasonably be regarded as a lower limit to the efficiency of the secretory mechanism. Some of the measurements were made in a potassium-free Ringer’s solution, and others with an external potassium concentration of 10mM. In the potassium-rich medium, both the sodium efflux and the oxygen consumption were increased, the proportion of the energy production required for sodium extrusion remaining roughly constant. The action of dinitrophenol and other metabolic inhibitors on the sodium efflux in sartorius muscles was examined, but there were no very obvious effects.

Abstract P412: Mitochondrial Metabolic Transcriptome Profiles During Cardiomyocyte Differentiation From Mouse And Human Pluripotent Stem Cells

2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Sung Woo Cho ◽  
Hyoung Kyu Kim ◽  
Jin Han ◽  
Ji-Hee Sung
Keyword(s):  
Stem Cells ◽  
Pluripotent Stem Cells ◽  
Oxidative Metabolism ◽  
Time Dependent ◽  
Lineage Commitment ◽  
Simultaneous Increase ◽  
Dependent Manner ◽  
Cardiomyocyte Differentiation ◽  
Cardiac Lineage ◽  
Mitochondrial Oxidative Metabolism

Simultaneous increase of myofibrils and mitochondria is a key process of cardiomyocyte differentiation from pluripotent stem cells (PSCs). Specifically, development of mitochondrial oxidative energy metabolism in cardiomyocytes is essential to providing the beating function. Although previous studies reported that mitochondrial oxidative metabolism have some correlation with the differentiation of cardiomyocytes, the mechanism by which mitochondrial oxidative metabolism is regulated and the link between cardiomyogenesis and mitochondrial function are still poorly understood. In the present study, we performed transcriptome analysis on cells at specific stages of cardiomyocyte differentiation from mouse embryonic stem cells (mESCs) and human induced PSCs (hiPSCs). We selected highly upregulated mitochondrial metabolic genes at cardiac lineage commitment and time-dependent manner during cardiomyocyte differentiation and identified the protein-protein interaction network connecting between mitochondrial metabolic and cardiac developmental genes. We found several mitochondrial metabolic regulatory genes at cardiac lineage commitment (Cck, Bdnf, Fabp4, Cebpa, Cdkn2a in mESC-derived cells and CCK, NOS3 in hiPSC-derived cells) and time-dependent manner during cardiomyocyte differentiation (Eno3, Pgam2, Cox6a2, Fabp3 in mESC-derived cells and PGAM2, SLC25A4 in hiPSC-derived cells). Notably, mitochondrial metabolic proteins are highly interacted with cardiac developmental proteins time-dependent manner during cardiomyocyte differentiation rather than cardiac lineage commitment. Furthermore, mitochondrial metabolic proteins are mainly interacted with cardiac muscle contractile proteins rather than cardiac transcription factors in cardiomyocyte. Therefore, mitochondrial metabolism is critical at cardiac maturation rather than cardiac lineage commitment.

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