Basal respiration or basal metabolic rate (BMR) is the minimal rate of metabolism required to support basic body functions, essential for maintenance only. BMR (in humans) is measured at rest 12 to 14 hours after eating in a physically and mentally relaxed state at thermally neutral room temperature. Maintenance energy requirements include mainly the metabolic costs of protein turnover and ion homeostasis. 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 oxycaloric equivalent) agree within errors of measurement (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, 'respiration' is not equivalent to 'metabolic rate'. Basal respiration in humans and skeletal muscle mitochondrial function (oxygen kinetics) are correlated (Larsen et al 2011 ). » MiPNet article
MitoPedia methods: Respirometry
MitoPedia topics: EAGLE
Basal respiration in physiology, cellular bioenergetics and mitochondrial physiology
|Gnaiger E (2013) Basal respiration in physiology, cellular bioenergetics and mitochondrial physiology. Mitochondr Physiol Network 2013-07-07.|
Abstract: Basal respiration is well defined in physiology. Terminology in mitochondrial physiology gains quality by reference to established concepts.
• O2k-Network Lab: AT Innsbruck Gnaiger E
Preparation: Intact cells, Permeabilized cells, Permeabilized tissue, Homogenate, Isolated mitochondria
Coupling state: LEAK, ROUTINE
Definition of basal metabolism in mammals and man
- Definition in Wikipedia
- Blaxter 1962  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 cellular and mitochondrial respiration
- Standard respiration refers to oxygen consumption measured with minimal motor activity, frequently made on anesthetized animals (Prosser, Brown 1961 ).
- 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 living cells, ROUTINE respiration varies as a function of cell cycle and substrate supply ([5,6]).
- Resting respiration in cells and mitochondrial preparations may refer to the LEAK state of minimum respiration (inhibition of phosphorylation, e.g. by oligomycin or deprivation of ADP]. If 'basal' is taken as 'minimum' (e.g. basal body temperature is the lowest body temperature attained during rest), then basal respiration in cells and mitochondria is the minimum respiration in the LEAK state [7,8]. A recently proposed terminology uses the term 'basal respiration' to describe ROUTINE respiration of living cells, which proceeds at an intermediate rather than minimum ATP demand . This definition lacks physiological context, is confusing, and its use is discouraged .
- 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 [7,8]. LEAK or basal respiration in mitochondrial preparations is obtained after inhibition of phosphorylation or in the absence of ADP in ET-pathway competent substrate states . LEAK or basal respiration is measured in living cells after inhibition of phosphorylation (e.g. oligomycin) and should be corrected for residual oxygen consumption (ROX ).
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, per volume, or per surface area of the body .
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- Gnaiger, Kemp 1990 Biochim Biophys Acta
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- Prosser CL, Brown FA 1961. Comparative animal physiology. Saunders.
- Gnaiger 2008 POS
- Pesta, Gnaiger 2012 Methods Mol Biol
- Gnaiger 2009 Int J Biochem Cell Biol
- Gnaiger 2020 BEC MitoPathways
- Brand, Nicholls 2011 Biochem J
- Gnaiger 1993 Pure Appl Chem