Energy transfer in mitochondrial oxidative phosphorylation. III. Interaction of adenosine diphosphate with high-energy intermediates

Biochemistry ◽  
1968 ◽  
Vol 7 (4) ◽  
pp. 1327-1333 ◽  
Author(s):  
Rudolf H. Eisenhardt ◽  
Otto. Rosenthal
Keyword(s):  
Energy Transfer ◽  
Oxidative Phosphorylation ◽  
Adenosine Diphosphate ◽  
High Energy ◽  
Mitochondrial Oxidative Phosphorylation

INFLUENCES OF THYROXINE AND INSULIN ON THE TURNOVER AND FATE OF HIGH-ENERGY PHOSPHATE

1964 ◽  
Vol 42 (6) ◽  
pp. 777-786 ◽  
Author(s):  
Dorothy S. Dow
Keyword(s):  
Skeletal Muscle ◽  
Energy Transfer ◽  
Adenosine Triphosphate ◽  
Cell Structure ◽  
Adenosine Diphosphate ◽  
High Energy ◽  
High Energy Phosphate ◽  
Nucleoside Phosphorylase ◽  
Mitochondrial Permeability ◽  
Energy Acceptor

Ingestion by the weanling rat of thyroxine in an amount greatly in excess of physiological requirements resulted in significant increases in the rates of turnover of the high-energy compounds phosphocreatine (PC), adenosine diphosphate (ADP), and adenosine triphosphate (ATP) and in significant decreases in their concentrations in skeletal muscle. Nucleoside phosphorylase and myokinase activities and rates of pyrophosphate splitting of ATP and of utilization of ATP for nuclear syntheses were unaltered in thyrotoxic muscle. The findings suggest that increased extramitochondrial utilization of ATP for glycolysis may be the factor responsible for the increased phosphorylating capacity of the thyrotoxic animal. An effect of thyroxine on mitochondrial permeability as well as on rate of formation of the high-energy intermediate would appear to explain the observed results.A further enhancement of the already markedly elevated thyrotoxic rate of phosphorylation was effected by the superimposition of insulin. Insulin also effected increases in the concentrations of the high-energy compounds. It is apparent that insulin acts by reducing the utilization of ATP for phosphorylation of glucose and thus increases the mitochondrial availability of high-energy acceptor. This increased mitochondrial affinity for high-energy compounds results in an enhancement of mitochondrial energy transfer processes.The findings appear to involve both thyroxine and insulin in the control of cell structure.

Carotid body O2 chemoreception and mitochondrial oxidative phosphorylation

1981 ◽  
Vol 51 (2) ◽  
pp. 438-446 ◽  
Author(s):  
E. Mulligan ◽  
S. Lahiri ◽  
B. T. Storey
Keyword(s):  
Oxidative Phosphorylation ◽  
Carotid Body ◽  
High Energy ◽  
Metabolic Inhibitors ◽  
Antimycin A ◽  
Mitochondrial Oxidative Phosphorylation ◽  
High Energy Phosphate ◽  
Afferent Fibers ◽  
Carbonyl Cyanide ◽  
Stimulation Of

The effect on carotid chemoreceptor afferents of oligomycin, an inhibitor of mitochondrial oxidative phosphorylation that does not affect energy conservation, was studied in 20 cats that were anesthetized, paralyzed, and artificially ventilated. Responses of single or a few chemoreceptor afferents to changes in arterial O2 tension (PaO2) at constant arterial CO2 tension were recorded. In addition, responses to nicotine, cyanide, and antimycin A or carbonyl cyanide p-tri-fluoromethoxyphenylhydrazone (FCCP) were tested in normoxia. Oligomycin (50-500 microgram) was administered by close intra-arterial injection, and the same tests were repeated at timed intervals. Initially, oligomycin caused vigorous stimulation of carotid chemoreceptor activity. Subsequently, although the afferent fibers were still active and could be vigorously stimulated by nicotine, they no longer responded to changes in PaO2 or to doses of cyanide, antimycin A, or FCCP. These results separate stimulation of chemoreceptor afferents by hypoxia and metabolic inhibitors and uncouplers from that by nicotine and suggest that intact oxidative phosphorylation, required for maintenance of the intracellular high-energy phosphate levels, forms the basis of O2 chemoreception in the carotid body.

Energy metabolism in patients with diabetes and heart failure

2019 ◽  
pp. 32-36
Keyword(s):  
Heart Failure ◽  
Energy Metabolism ◽  
Oxidative Phosphorylation ◽  
Energy Demand ◽  
Glucose Oxidation ◽  
High Energy ◽  
Energy Deficit ◽  
Diabetic Patients ◽  
Mitochondrial Oxidative Phosphorylation ◽  
Myocardial Energy Metabolism

The heart has a very high energy demand, which is mostly met by mitochondrial oxidative phosphorylation and, to a lesser extent, by glycolysis. In heart failure, there are substantial alterations in myocardial energy metabolism that lead to an “energy-deficient” state. This includes a marked reduction in overall mitochondrial oxidative phosphorylation and an uncoupling between high glycolysis rates and low glucose oxidation, which together contributes to the energy deficit and deteriorates contractile dysfunction. Cardiac ketone oxidation is also increased in heart failure, although it has yet to be determined whether this is an adaptive or maladaptive alteration. Diabetes is a major risk factor for heart failure development. It induces alterations in myocardial energy metabolism and is often associated with ventricular dysfunction. Similar to heart failure, a major change in myocardial energy metabolism in diabetic patients is a reduction in glucose oxidation, which negatively influences cardiac function. In both heart failure and diabetes, a growing body of evidence suggests that targeting myocardial energy metabolism by optimizing cardiac energy substrate preference could be a potential therapeutic approach to improve patient outcomes.

Mitochondrial oxidative phosphorylation in hearts subjected to Ca2+ depletion and Ca2+ repletionThis article is one of a selection of papers published in a special issue celebrating the 125th anniversary of the Faculty of Medicine at the University of Manitoba.

2009 ◽  
Vol 87 (10) ◽  
pp. 789-797 ◽  
Author(s):  
Zhanna Makazan ◽  
Harjot K. Saini-Chohan ◽  
Naranjan S. Dhalla
Keyword(s):  
Oxidative Phosphorylation ◽  
Mitochondrial Function ◽  
Cell Damage ◽  
Respiratory Control ◽  
Myocardial Cell ◽  
High Energy ◽  
Mitochondrial Oxidative Phosphorylation ◽  
Rat Hearts ◽  
Intracellular Ca ◽  
125Th Anniversary

Repletion of Ca2+ in the Ca2+-depleted heart has been shown to produce cardiac dysfunction, myocardial cell damage, intracellular Ca2+ overload, and defects in sarcolemmal and sarcoplasmic reticulum function (Ca2+ paradox). Although these alterations in the Ca2+-paradox heart are associated with a depression in the high-energy phosphate stores, little information regarding changes in mitochondrial oxidative phosphorylation is available. Perfusion of rat hearts with Ca2+-free medium for 5 min followed by reperfusion with a medium containing 1.25 mmol/L Ca2+ for 10 min depressed mitochondrial state 3 respiration, respiratory control index, ADP/O ratio, and rate of oxidative phosphorylation without any change in state 4 respiration. These alterations were partially prevented when the reperfusion was carried out with a medium containing low Ca2+ (0.10–0.50 mmol/L). Treatment of heart with inhibitors of sarcolemmal Ca2+ channels (verapamil and diltiazem) or inhibitors of Na+/Ca2+ exchange (KB-R7943) and Na+/H+ exchange (amiloride) failed to modify changes in mitochondrial function due to Ca2+ paradox. Likewise, antioxidants N-acetylcysteine and N-(2-mercaptopropionyl)-glycine and an oxyradical-scavenging mixture of superoxide dismutase and catalase were ineffective in preventing the mitochondrial alterations in the Ca2+-paradox heart. Incubation of mitochondria with various concentrations of Ca2+ inhibited oxidative phosphorylation; this Ca2+-induced change in mitochondrial function was not affected by different oxyradical-scavenging systems. These observations suggest that defects in mitochondrial function in the Ca2+-paradox heart may be due to the occurrence of intracellular Ca2+ overload rather than the development of oxidative stress.

Dependence of Platelet Adenyl Cyclase System on Oxidative Phosphorylation

1975 ◽  
Vol 34 (01) ◽  
pp. 042-049 ◽  
Author(s):  
Shuichi Hashimoto ◽  
Sachiko Shibata ◽  
Bokro Kobayashi
Keyword(s):  
Cyclic Amp ◽  
Oxidative Phosphorylation ◽  
Sodium Succinate ◽  
Potassium Cyanide ◽  
Adenyl Cyclase ◽  
Mitochondrial Oxidative Phosphorylation ◽  
Adenyl Cyclase Activity ◽  
Intact Rabbit ◽  
Adenyl Cyclase System ◽  
Cyclic Amp Synthesis

SummaryThe radioactive adenosine 3′,5′-monophosphate (cyclic AMP) level derived from 8-14C adenine in intact rabbit platelets decreased in the presence of mitochondrial inhibitor (potassium cyanide) or uncoupler (sodium azide), and markedly increased by the addition of NaF, monoiodoacetic acid (MIA), or 2-deoxy-D-glucose. The stimulative effect of the glycolytic inhibitors was distinctly enhanced by the simultaneous addition of sodium succinate. MIA did neither directly stimulate the adenyl cyclase activity nor inhibit the phosphodiesterase activity. These results suggest that cyclic AMP synthesis in platelets is closely linked to mitochondrial oxidative phosphorylation.

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