scholarly journals Does the membrane pacemaker theory of metabolism explain the size dependence of metabolic rate in marine mussels?

2017 ◽  
Vol 220 (8) ◽  
pp. 1423-1434 ◽  
Author(s):  
Alexey Sukhotin ◽  
Natalia Fokina ◽  
Tatiana Ruokolainen ◽  
Christian Bock ◽  
Hans-Otto Pörtner ◽  
...  
Keyword(s):  
Metabolic Rate ◽  
Size Dependence ◽  
Marine Mussels ◽  
Membrane Pacemaker

scholarly journals Changes in body temperature influence the scaling of and aerobic scope in mammals

2006 ◽  
Vol 3 (1) ◽  
pp. 100-103 ◽  
Author(s):  
James F Gillooly ◽  
Andrew P Allen
Keyword(s):  
Body Size ◽  
Metabolic Rate ◽  
Size Dependence ◽  
Maximal Activity ◽  
Scaling Exponent ◽  
Temperature Influence ◽  
Aerobic Scope ◽  
Metabolic Scope ◽  
Single Power ◽  
Maximum Metabolic Rate

Debate on the mechanism(s) responsible for the scaling of metabolic rate with body size in mammals has focused on why the maximum metabolic rate ( ) appears to scale more steeply with body size than the basal metabolic rate (BMR). Consequently, metabolic scope, defined as /BMR, systematically increases with body size. These observations have led some to suggest that and BMR are controlled by fundamentally different processes, and to discount the generality of models that predict a single power-law scaling exponent for the size dependence of the metabolic rate. We present a model that predicts a steeper size dependence for than BMR based on the observation that changes in muscle temperature from rest to maximal activity are greater in larger mammals. Empirical data support the model's prediction. This model thus provides a potential theoretical and mechanistic link between BMR and .

Mammalian metabolism: insights from arid zone reptiles.

2004 ◽  
Vol 26 (1) ◽  
pp. 111
Author(s):  
AJ Hulbert ◽  
PL Else
Keyword(s):  
Metabolic Rate ◽  
Membrane Lipids ◽  
Arid Zone ◽  
Membrane Surface ◽  
Size Variation ◽  
High Mass ◽  
Metabolic Rates ◽  
Mammal Species ◽  
Mechanistic Basis ◽  
Membrane Pacemaker

Mammals, being endotherms have very high metabolic rates compared to ectothermic reptiles. Similarly, small mammals have high rates of mass-specific metabolism compared to larger mammals. This review examines the mechanistic basis of why particular mammal species have a specific metabolic rate. Initial studies compared mammals with arid zone reptile species of the same size and Tb. Mammals have larger internal organs, with more mitochondrial membrane surface area than the reptiles. The cells of mammals are leakier to Na+ ions and their mitochondrial membranes are leakier to H+ ions than in reptile cells. These leakier membranes have membrane lipids that are polyunsaturated and less monounsaturated than their less leaky counterparts. Examination of the cellular basis of allometric variation in metabolism in mammals reveals very similar findings with polyunsaturated membranes associated with the high mass-specific metabolic rates of small mammal species and monounsaturated membranes with low rates of metabolism of large mammals. These findings have resulted in the development of the ?membrane pacemaker? theory of metabolism, which proposes that membrane bilayer composition is regulated in animals and that highly polyunsaturated membranes result in enhanced molecular activity of membrane proteins and in turn this results in an elevated metabolic rate of cells, tissues and consequently whole animals. This theory is also supported by the recent examination of the basis of body-size variation in the metabolic rates of birds. The ?membrane pacemaker? theory of metabolism is currently the only explanation of the mechanisms determining the metabolic rate and thus the cost of living of animals. It has implications for the effect of food habits on metabolism and the relationship between metabolism and lifespan.

scholarly journals Setting the pace of life: membrane composition of flight muscle varies with metabolic rate of hovering orchid bees

2015 ◽  
Vol 282 (1802) ◽  
pp. 20142232 ◽  
Author(s):  
Enrique Rodríguez ◽  
Jean-Michel Weber ◽  
Benoît Pagé ◽  
David W. Roubik ◽  
Raul K. Suarez ◽  
...  
Keyword(s):  
Metabolic Rate ◽  
Body Mass ◽  
Relative Abundance ◽  
Flight Muscle ◽  
Muscle Membrane ◽  
Rate Variation ◽  
Membrane Composition ◽  
Functional Link ◽  
Orchid Bees ◽  
Membrane Pacemaker

Patterns of metabolic rate variation have been documented extensively in animals, but their functional basis remains elusive. The membrane pacemaker hypothesis proposes that the relative abundance of polyunsaturated fatty acids in membrane phospholipids sets the metabolic rate of organisms. Using species of tropical orchid bees spanning a 16-fold range in body size, we show that the flight muscles of smaller bees have more linoleate (%18 : 3) and stearate (%18 : 0), but less oleate (%18 : 1). More importantly, flight metabolic rate (FlightMR) varies with the relative abundance of 18 : 3 according to the predictions of the membrane pacemaker hypothesis. Although this relationship was found across large differences in metabolic rate, a direct association could not be detected when taking phylogeny and body mass into account. Higher FlightMR, however, was related to lower %16 : 0, independent of phylogeny and body mass. Therefore, this study shows that flight muscle membrane composition plays a significant role in explaining diversity in FlightMR, but that body mass and phylogeny are other factors contributing to their variation. Multiple factors are at play to modulate metabolic capacity, and changing membrane composition can have gradual and stepwise effects to achieve a new range of metabolic rates. Orchid bees illustrate the correlated evolution between membrane composition and metabolic rate, supporting the functional link proposed in the membrane pacemaker hypothesis.

scholarly journals Energetic inequivalence in eusocial insect colonies

2011 ◽  
Vol 7 (4) ◽  
pp. 611-614 ◽  
Author(s):  
John P. DeLong
Keyword(s):  
Body Size ◽  
Metabolic Rate ◽  
Size Dependence ◽  
Population Level ◽  
The Body ◽  
Laboratory Studies ◽  
Eusocial Insects ◽  
Direct Measurements ◽  
Average Body ◽  
Colony Level

The energetic equivalence rule states that population-level metabolic rate is independent of average body size. This rule has been both supported and refuted by allometric studies of abundance and individual metabolic rate, but no study, to my knowledge, has tested the rule with direct measurements of whole-population metabolic rate. Here, I find a positive scaling of whole-colony metabolic rate with body size for eusocial insects. Individual metabolic rates in these colonies scaled with body size more steeply than expected from laboratory studies on insects, while population size was independent of body size. Using consumer-resource models, I suggest that the colony-level metabolic rate scaling observed here may arise from a change in the scaling of individual metabolic rate resulting from a change in the body size dependence of mortality rates.

Development of new predictive equations for basal metabolic rate in Iranian healthy adults: negligible effect of sex

2020 ◽  
pp. 1-10
Author(s):  
Bahareh Nikooyeh ◽  
Nastaran Shariatzadeh ◽  
Ali Kalayi ◽  
Maliheh Zahedirad ◽  
Tirang R. Neyestani
Keyword(s):  
Metabolic Rate ◽  
Thyroid Function ◽  
Basal Metabolic Rate ◽  
Age Groups ◽  
Thyroid Function Tests ◽  
Anthropometric Measures ◽  
Predictive Equations ◽  
Normal Thyroid Function ◽  
Asian People ◽  
Predictive Formulas

Abstract. Some studies have reported inaccuracy of predicting basal metabolic rate (BMR) by using common equations for Asian people. Thus, this study was undertaken to develop new predictive equations for the Iranian community and also to compare their accuracy with the commonly used formulas. Anthropometric measures and thyroid function were evaluated for 267 healthy subjects (18–60 y). Indirect calorimetry (InCal) was performed only for those participants with normal thyroid function tests (n = 252). Comparison of predicted RMR (both kcal/d and kcal.kg.wt−1.d−1) using current predictive formulas and measured RMR revealed that Harris-Benedict and FAO/WHO/UNU significantly over-estimated and Mifflin-St. Jeor significantly under-estimated RMR as compared to InCal measurements. In stepwise regression analysis for developing new equations, the highest r2 (=0.89) was from a model comprising sex, height and weight. However, further analyses revealed that unlike the subjects under 30 y, the association between age and the measured RMR in subjects 30 y and plus was negative (r = −0.241, p = 0.001). As a result, two separate equations were developed for these two age groups. Over 80 percent of variations were covered by the new equations. In conclusion, there were statistical significant under- and over-estimation of RMR using common predictive equations in our subjects. Using the new equations, the accuracy of the calculated RMR increased remarkably.

Nutrient pattern of unsaturated fatty acids and vitamin E increase resting metabolic rate of overweight and obese women

2020 ◽  
pp. 1-9
Author(s):  
Habib Yarizadeh ◽  
Leila Setayesh ◽  
Caroline Roberts ◽  
Mir Saeed Yekaninejad ◽  
Khadijeh Mirzaei
Keyword(s):  
Vitamin E ◽  
Metabolic Rate ◽  
Unsaturated Fatty Acids ◽  
Resting Metabolic Rate ◽  
Blood Parameters ◽  
Cross Sectional Study ◽  
Obese Women ◽  
Cross Sectional ◽  
Dietary Nutrients ◽  
Nutrient Patterns

Abstract. Objectives: Obesity plays an important role in the development of chronic diseases including cardiovascular disease and diabetes. A low resting metabolic rate (RMR) for a given body size and composition is a risk factor for obesity, however, there is limited evidence available regarding the association of nutrient patterns and RMR. The aim of this study was to determine the association of nutrient patterns and RMR in overweight and obese women. Study design: This cross-sectional study was conducted on 360 women who were overweight or obese. Method: Dietary intake was assessed using a semi-quantitative standard food frequency questionnaire (FFQ). Nutrient patterns were also extracted by principal components analysis (PCA). All participants were evaluated for their body composition, RMR, and blood parameters. Result: Three nutrient patterns explaining 64% of the variance in dietary nutrients consumption were identified as B-complex-mineral, antioxidant, and unsaturated fatty acid and vitamin E (USFA-vit E) respectively. Participants were categorized into two groups based on the nutrient patterns. High scores of USFA-vit E pattern was significantly associated with the increase of RMR (β = 0.13, 95% CI = 0.79 to 68.16, p = 0.04). No significant associations were found among B-complex-mineral pattern (β = −0.00, 95% CI = −49.67 to 46.03, p = 0.94) and antioxidant pattern (β = 0.03, 95% CI −41.42 to 22.59, p = 0.56) with RMR. Conclusion: Our results suggested that the “USFA-vit E” pattern (such as PUFA, oleic, linoleic, vit.E, α-tocopherol and EPA) was associated with increased RMR.

Quantitative measurement of cerebral metabolic rate of glucose by means of dual-head coincidence gamma camera and 2-deoxy-2- [18F] fluoro-D-glucose

2005 ◽  
Vol 25 (1_suppl) ◽  
pp. S670-S670
Author(s):  
Katsufumi Kajimoto ◽  
Naohiko Oku ◽  
Yasuyuki Kimura ◽  
Makiko Tanaka ◽  
Hiroki Kato ◽  
...  
Keyword(s):  
Metabolic Rate ◽  
Gamma Camera ◽  
Quantitative Measurement ◽  
Cerebral Metabolic Rate
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