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Basal respiration

From Bioblast


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Basal respiration

Description

Basal respiration or basal metabolic rate (BMR) is the minimal rate of metabolism required to support basic body functions, required for maintenance only. BMR (in humans) is measured at rest 12 to 14 hours after eating. Maintenance energy requirements include particularly the metabolic costs of ion homeostasis and protein turnover.

In many aerobic organisms, and particularly well studied in mammals, BMR is fully aerobic, i.e. direct calorimetry (measurement of heat dissipation) and indirect calorimetry (measurement of oxygen consumption multiplied by the oxyenthalpic equivalent) agree very closely (Blaxter KL 1962. The energy metabolism of ruminants. Hutchinson, London: 332 pp). In many cultured mammalian cells, aerobic glycolysis contributes to total ATP turnover (Gnaiger and Kemp 1990), and under these conditions, basal 'respiration' is not equivalent to basal 'metabolic rate'.

Abbreviation: BMR

Reference: Larsen_2011_FASEBJ, Gnaiger_1990_BBA


MitoPedia topics: "Respiratory state" is not in the list (Enzyme, Medium, Inhibitor, Substrate and metabolite, Uncoupler, Sample preparation, Permeabilization agent, EAGLE, MitoGlobal Organizations, MitoGlobal Centres, ...) of allowed values for the "MitoPedia topic" property. Respiratory state"Respiratory state" is not in the list (Enzyme, Medium, Inhibitor, Substrate and metabolite, Uncoupler, Sample preparation, Permeabilization agent, EAGLE, MitoGlobal Organizations, MitoGlobal Centres, ...) of allowed values for the "MitoPedia topic" property. 

Definitions of basal metabolism

  • Blaxter KL 1962. The energy metabolism of ruminants. Hutchinson, London, p. 79 f: "It has long been realized that if an animal is given no food and certain other conditions are met, a measurement of heat production represents that animal's minimal energy demand. Measurments of this type are called basal metabolism determinations, and the conditions for the measurement are, firstly, that the animal should be in a post-absorptive state, secondly, that it should be in a state of muscular repose though not asleep and, lastly, that the environment in which the measurement is made should be neither so hot nor so cold as to cause and increase in the metabolism. This last condition means that the animal should be in a 'thermoneutral' environment." .. "In man, basal metabolism is measured with the subject in repose but not asleep. Sleep during fasting depresses metabolism by about 7%." .. "With man, an overnight fast is sufficient to achieve a post-absorptive state and to reduce metabolism to a basal level. Indeed it is even permissible for clinical purposes to take a very slight ultra-continental breakfast before the measurement is made, since it has little effect on the metabolism determined a few hours later."

States and rates

Respiratory states: from physiology to mitochondrial respiration

  • Standard respiration refers to oxygen consumption measured with minimal motor activity, frequently made on anesthetized animals (Prosser CL, Brown FA 1961. Comparative Animal Physiology. Saunders).
  • Routine respiration is usually higher than standard or basal respiration due to the oxygen consumption required to sustain various routine activities, not restricted to locomotory activity, but including the effects of food or substrate availability, growth conditions. In intact cells, ROUTINE respiration varies as a function of cell cycle and substrate supply.
  • LEAK respiration is the energy expenditure required mainly to compensate for the proton leak through the inner mitochondrial membrane, but additionally including energy expenditure caused by proton slip and cation cycling through the inner mitochondrial membrane in general.


Metabolic energy flow, flux, and rate

The term metabolic 'rate' is frequently used for energy flow or metabolic flux. Energy flow (oxygen flow) is system-specific quantity related to a defined system, and expressed per system (per individual organism, per million cells, or per experimental system). Metabolic flux (oxygen flux) is a system size-specific quantity, expressed per kg body weight or per surface area of the body.