Thinking with and without oxygen: energy metabolism in vertebrate brains

1988 ◽  
Vol 66 (5) ◽  
pp. 1041-1045 ◽  
Author(s):  
Raul K. Suarez
Keyword(s):  
Energy Metabolism ◽  
Metabolic Rate ◽  
Anoxia Tolerance ◽  
Limited Extent ◽  
Eeg Activity ◽  
Pasteur Effect ◽  
Atp Production ◽  
Ion Gradients ◽  
Glycolytic Atp ◽  
Metabolic Arrest

A survey of the information available on the biochemical differences between anoxia-sensitive brains of mammals and anoxia-tolerant brains of aquatic turtles reveals that the latter maintain membrane ion gradients, ATP concentrations, and, to a limited extent, electroencephalographic (EEG) activity, while metabolic rate is depressed during prolonged anoxia. In contrast, mammalian brains are unable to maintain ATP concentrations, ion gradients, and EEG activity during ischemia or anoxia despite a dramatic (albeit transient) Pasteur effect. This evidence indicates that rates of ATP utilization decrease during anoxia in anoxia-tolerant brains, while they are maintained (and not matched by glycolytic ATP production) in anoxia-sensitive brains. The implications with respect to possible mechanisms of "metabolic arrest" and the evolution of anoxia tolerance in vertebrate brains are discussed.

Evolutionary Consequences of Tradeoffs between Yield and Rate of ATP Production

2002 ◽  
Vol 216 (1) ◽  
Author(s):  
Thomas Pfeiffer ◽  
Sebastian Bonhoeffer
Keyword(s):  
Game Theory ◽  
Population Dynamics ◽  
Energy Metabolism ◽  
Adenosine Triphosphate ◽  
Organic Material ◽  
High Yield ◽  
Atp Production ◽  
Cellular Processes ◽  
Quantitative Properties ◽  
Evolutionary Consequences

Adenosine triphosphate (ATP) is a key compound in the energy metabolism of cells and is required to drive vital biochemical reactions. In heterotrophic organisms ATP production is coupled to the degradation of energy-rich organic material taken up from the environment. In the transfer of the environmental energy to cellular processes heterotrophs face a tradeoff, since the conversion of the environmental energy into ATP cannot be both maximally fast and efficient. Here we show how tradeoffs between rate and yield of ATP production arise firstly from thermodynamical principles, and secondly for the ATP production by respiration and fermentation. Using methods derived from game theory and population dynamics we investigate the evolutionary consequences for both tradeoffs. We show that spatially structured environments enable the evolution of efficient pathways with high yield. The strategies of ATP production realized in a population, however, depend on the quantitative properties of the tradeoffs.

scholarly journals Effect of capsinoids on energy metabolism in human subjects

2009 ◽  
Vol 103 (1) ◽  
pp. 38-42 ◽  
Author(s):  
Jose E. Galgani ◽  
Donna H. Ryan ◽  
Eric Ravussin
Keyword(s):  
Blood Pressure ◽  
Energy Metabolism ◽  
Metabolic Rate ◽  
Human Subjects ◽  
Acute Effect ◽  
Molecular Structures ◽  
Acute Effects ◽  
Axillary Temperature ◽  
Double Blind ◽  
Different Doses

Capsinoids are non-pungent compounds with molecular structures similar to capsaicin, which has accepted thermogenic properties. To assess the acute effect of a plant-derived preparation of capsinoids on energy metabolism, we determined RMR and non-protein respiratory quotient (NPRQ) after ingestion of different doses of the capsinoids. Thirteen healthy subjects received four doses of the capsinoids (1, 3, 6 and 12 mg) and placebo using a crossover, randomised, double-blind trial. After a 10 h overnight fast as inpatients, RMR was measured by indirect calorimetry for 45 min before and 120 min after ingesting capsinoids or placebo. Blood pressure and axillary temperature were measured before ( − 55 and − 5 min) and after (60 and 120 min) dosing. Before dosing, mean RMR was 6247 (se92) kJ/d and NPRQ was 0·86 (se0·01). At 120 min after dosing, metabolic rate and NPRQ remained similar across the four capsinoids and placebo doses. Capsinoids also had no influence on blood pressure or axillary temperature. Capsinoids provided in four doses did not affect metabolic rate and fuel partitioning in human subjects when measured 2 h after exposure. Longer exposure and higher capsinoids doses may be required to cause meaningful acute effects on energy metabolism.

Cerebral anoxia tolerance in turtles: regulation of intracellular calcium and pH

1992 ◽  
Vol 263 (6) ◽  
pp. R1298-R1302
Author(s):  
P. E. Bickler
Keyword(s):  
Intracellular Calcium ◽  
Brain Slices ◽  
Calcium Flux ◽  
Anoxia Tolerance ◽  
Acetoxymethyl Ester ◽  
Fluorescent Indicators ◽  
Cerebral Anoxia ◽  
Atp Production ◽  
Laboratory Rats ◽  
Inhibition Of Glycolysis

To investigate mechanisms of cerebral anoxia tolerance, cerebrocortical intracellular calcium ([Ca2+]i) and pH (pHi) regulation were compared in turtles (Trachemys scripta) and laboratory rats. [Ca2+]i and pHi in living 200 to 300-microns-thick cortical brain slices were measured with the fluorescent indicators fura-2/acetoxymethyl ester (AM) and 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein during exposure to anoxia. Within 5 min, [Ca2+]i increased to > 1,000 nM in rat brain slices exposed to anoxia but [Ca2+]i was normal even after 5 h of anoxia in turtles. ATP levels remained normal in anoxic turtle brain but fell rapidly in rats. During anoxia, pHi fell by 0.25 +/- 0.08 pH units in rats but only 0.10 +/- 0.04 in turtles (P < 0.05). Inhibition of glycolysis in anoxic turtle brain with iodoacetate resulted in large increases in [Ca2+]i but prior exposure of slices to anoxia resulted in greatly attenuated calcium entry. The reduction in calcium flux was greater with increasing exposure to anoxia, suggesting progressive arrest of calcium channel activity. Tolerance of cerebral anoxia in turtles may be related to anaerobic ATP production, arrest of calcium channels, and attenuation of changes in pHi.

Metformin Collaborates With PINK1/Mfn2 Overexpression Prevented Isoproterenol-Induced Cardiomyocyte Injury By Improving Mitochondrial Function

2021 ◽  
Author(s):  
Zhuang Ma ◽  
Zuheng Liu ◽  
Yuting Xue ◽  
Hao Zhang ◽  
Wenjun Xiong ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Energy Metabolism ◽  
Mitochondrial Membrane Potential ◽  
Mitochondrial Biogenesis ◽  
Mitochondrial Membrane ◽  
Mitochondrial Morphology ◽  
Dependent Manner ◽  
Combination Strategy ◽  
Mitochondrial Energy Metabolism ◽  
Atp Production

Abstract Background: Both mitochondrial quality control and energy metabolism are critical in maintaining the physiological function of cardiomyocytes. Previous studies indicated that PGC-1α is a transcription co-activator in promoting mitochondrial energy metabolism which would be beneficial for cardiomyocytes. However, PGC-1α overexpression in heart tissues could also result in the development of cardiomyopathy. This discrepancy in vivo and in vitro might be due to neglecting the elimination of damaged mitochondrial. Thus, an integration strategy of mitochondrial biogenesis and mitophagy might be beneficial.Methods: We studied the function of PINK1 in mitophagy in isoproterenol (Iso)-induced cardiomyocyte injury. Adenovirus was used to provoke an overexpression of the PINK1/Mfn2 protein. Mitochondrial morphology was examined via electron microscopy and confocal microscopy. Cardiomyocytes injury were measured by mitochondrial membrane potential (MMP), reactive oxygen species (ROS) and apoptosis. Metformin was used to increase mitochondrial biogenesis, the level of which was detected via immunoblotting. Additionally, mitochondrial respiratory function was measured by ATP production and oxygen consumption rate (OCR). Results: Cardiomyocytes treated with Iso had high levels of PINK1 and low levels of Mfn2 in a time-dependent manner. PINK1 overexpression promoted mitophagy, alleviated Iso-induced reduction in MMP, reduced ROS production and the apoptotic rate. In addition to increasing mitophagy, metformin could promote mitochondrial biogenensis and the overexpression of Mfn2 induce mitochondrial fusion. Moreover, metformin treatment and PINK1/Mfn2 overexpression reduced the mitochondrial dysfunction by inhibiting the generation of ROS, and leading to an increase in both ATP production and mitochondrial membrane potential in Iso-induced cardiomyocytes injury. Conclusion: Our findings indicate that a combination strategy may help ameliorate myocardial injury through mitophagy and mitochondrial biogenesis.

Protein and energy metabolism in the pre-implantation cattle embryo

2001 ◽  
Vol 26 (2) ◽  
pp. 443-446 ◽  
Author(s):  
D.G. Morris ◽  
P. Humpherson ◽  
H.J. Leese ◽  
J.M. Sreenan
Keyword(s):  
Amino Acids ◽  
Protein Synthesis ◽  
Amino Acid ◽  
Energy Metabolism ◽  
Metabolic Rate ◽  
Protein Content ◽  
Amino Acid Uptake ◽  
Acid Uptake ◽  
Glucose Utilisation ◽  
Embryonic Loss

AbstractThere is no information on the metabolism of the cattle embryo during the period from day 8 to 16 a period of greatest embryonic loss. In this study the rate of protein synthesis and phosphorylation was measured in 13 to 15 day old cattle embryos. The rate of glucose utilisation and amino acid uptake/efflux by day 14 to 16 embryos was also measured. Protein synthesis and phosphorylation activity when expressed per unit of protein decreased with increasing embryo size and age. Similarly the rate of glucose utilisation was greatest for the earlier day 14 embryos. Embryos differed in their requirement for different amino acids. The pattern of uptake/efflux was similar to that of the earlier day 7 embryo. This study suggests that the metabolic rate of cattle embryos expressed per unit of protein content tends to decrease with increasing age and size from the initial burst of activity at day 13 around the time that expansion of the embryo begins.

scholarly journals Evidence for a negative Pasteur effect in articular cartilage

1997 ◽  
Vol 321 (1) ◽  
pp. 95-102 ◽  
Author(s):  
Robert B. LEE ◽  
Jill P. G. URBAN
Keyword(s):  
Articular Cartilage ◽  
Glucose Uptake ◽  
Lactate Production ◽  
Pasteur Effect ◽  
Anoxic Conditions ◽  
Atp Production ◽  
Bovine Articular Cartilage ◽  
Atp Concentration ◽  
O2 Concentration ◽  
Lactate Formation

Uptake of external glucose and production of lactate were measured in freshly-excised bovine articular cartilage under O2 concentrations ranging from 21% (air) to zero (N2-bubbled). Anoxia (O2 concentration < 1% in the gas phase) severely inhibited both glucose uptake and lactate production. The decrease in lactate formation correlated closely with the decrease in glucose uptake, in a mole ratio of 2:1. This reduction in the rate of glycolysis in anoxic conditions is seen as evidence of a negative Pasteur effect in bovine articular cartilage. Anoxia also suppressed glycolysis in articular cartilage from horse, pig and sheep. Inhibitors acting on the glycolytic pathway (2-deoxy-d-glucose, iodoacetamide or fluoride) strongly decreased aerobic lactate production and ATP concentration, consistent with the belief that articular cartilage obtains its principal supply of ATP from substrate-level phosphorylation in glycolysis. Azide or cyanide lowered the ATP concentration in aerobic cartilage to approximately the same extent as did anoxia but, because glycolysis (lactate production) was also inhibited by these treatments, the importance of any mitochondrial ATP production could not be assessed. A negative Pasteur effect would make chondrocytes particularly liable to suffer a shortage of energy under anoxic conditions. Incorporation of [35S]sulphate into proteoglycan was severely curtailed by treatments, such as anoxia, which decreased the intracellular concentration of ATP.

scholarly journals Altered mitochondrial fusion drives defensive glutathione synthesis in cells able to switch to glycolytic ATP production

2021 ◽  
Vol 1868 (1) ◽  
pp. 118854
Author(s):  
David A. Patten ◽  
Shawn McGuirk ◽  
Ujval Anilkumar ◽  
Ghadi Antoun ◽  
Karan Gandhi ◽  
...  
Keyword(s):  
Mitochondrial Fusion ◽  
Glutathione Synthesis ◽  
Atp Production ◽  
Glycolytic Atp ◽  
In Cells

scholarly journals Basal Metabolic Rate and Body Composition Predict Habitual Food and Macronutrient Intakes: Gender Differences

Nutrients ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2653 ◽  
Author(s):  
Xinyan Bi ◽  
Ciarán G. Forde ◽  
Ai Ting Goh ◽  
Christiani Jeyakumar Henry
Keyword(s):  
Gender Differences ◽  
Body Composition ◽  
Energy Metabolism ◽  
Metabolic Rate ◽  
Basal Metabolic Rate ◽  
Energy Homeostasis ◽  
Macronutrient Intake ◽  
Dietary Record ◽  
Males And Females ◽  
The Relationship

The underlying mechanisms that regulate energy homeostasis and food intake are not fully understood. Moreover, little research has been performed on the relation of body composition with habitual macronutrient intake among free-living populations. Since body composition and energy metabolism differ between males and females, we aimed to determine whether the relationship between body composition and habitual macronutrient intakes is gender-dependent. In this cross-sectional study, 261 participants (99 males) were recruited from Singapore. Macronutrient intake was evaluated from a three-day self-reported dietary record. Body composition and basal metabolic rate (BMR) were determined by using dual-energy X-ray absorptiometry (DEXA) and indirect calorimetry, respectively. Our results show that both BMR (p < 0.001) and lean body mass (LBM, p < 0.001) predicted daily energy intake (EI). LBM was positively associated with intakes of protein (PRO) and fat (FAT) in females, but not in males. This relationship persisted even after adjustment for fat mass (FM). On the other hand, no significant associations between FM and macronutrient intake were observed in both males and females. Therefore, the relationship between habitual macronutrient intake, LBM, and BMR is gender-dependent. Elucidating the gender differences in energy metabolism is important for understanding the factors that regulate energy homeostasis and can subsequently help better manage energy balance.

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