The reconstruction of Kleiber's law at the organ-tissue level.
The relationship between resting energy expenditure (REE) (kJ/d) and body mass (M) (kg) is a cornerstone in the study of energy physiology. By expressing REE as a function of body mass observed across mammals, Kleiber formulated the now classic equation: REE = 293M(0.75). The biological processes underlying Kleiber's law have been a topic of long-standing interest and speculation. In the present report we develop a new perspective of Kleiber's law by developing an organ-tissue level REE model consisting of five components: liver, brain, kidneys, heart and remaining tissues. The resting thermal output of each component is the product of the component's specific resting metabolic rate (K) and mass (T). With increasing body size, the K values for all five components had negative exponents and were directly proportional to M(-0.08--0.27), and all component T values were directly proportional to M(0.76-1.01). The resulting exponents of the product (K x T) were M(0.60-0.86) for the five components. Although the (K x T) values of individual components do not scale equally, their combined formula (286M(0.76)) is similar to that observed by Kleiber on the whole-body level. Modeling mammalian REE at the organ-tissue level provides new insights and pathways for future mechanistic explorations of REE-body composition relationships.
Wang
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Obesity Research Center, St. Luke's-Roosevelt Hospital, Columbia University, College of Physicians and Surgeons, New York, NY 10025, USA. zw28@columbia.edu
O'Connor
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Heshka
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Heymsfield
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D000818:Animals; D001481:Basal Metabolism / Q000502:physiology*; D001823:Body Composition; D001921:Brain / Q000378:metabolism; D002415:Cats; D004285:Dogs; D006801:Humans; D007668:Kidney / Q000378:metabolism; D008099:Liver / Q000378:metabolism; D008954:Models, Biological; D009206:Myocardium / Q000378:metabolism; D011817:Rabbits; D051381:Rats; D013045:Species Specificity