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Titolo:
CELLULAR-ENERGY UTILIZATION AND MOLECULAR-ORIGIN OF STANDARD METABOLIC-RATE IN MAMMALS
Autore:
ROLFE DFS; BROWN GC;
Indirizzi:
UNIV CAMBRIDGE,DEPT BIOCHEM,TENNIS COURT RD CAMBRIDGE CB2 1QW ENGLAND
Titolo Testata:
Physiological reviews
fascicolo: 3, volume: 77, anno: 1997,
pagine: 731 - 758
SICI:
0031-9333(1997)77:3<731:CUAMOS>2.0.ZU;2-W
Fonte:
ISI
Lingua:
ENG
Soggetto:
MITOCHONDRIAL OXIDATIVE-PHOSPHORYLATION; BROWN ADIPOSE-TISSUE; ATP-CONSUMING PROCESSES; TOP-DOWN APPROACH; SATURATION TRANSFER MEASUREMENTS; RELATIVE PROTON STOICHIOMETRIES; DIET-INDUCED THERMOGENESIS; BETWEEN-SUBJECTS VARIATION; PERFUSED SKELETAL-MUSCLE; ASCITES TUMOR-CELLS;
Tipo documento:
Review
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
221
Recensione:
Indirizzi per estratti:
Citazione:
D.F.S. Rolfe e G.C. Brown, "CELLULAR-ENERGY UTILIZATION AND MOLECULAR-ORIGIN OF STANDARD METABOLIC-RATE IN MAMMALS", Physiological reviews, 77(3), 1997, pp. 731-758

Abstract

The molecular origin of standard metabolic rate and thermogenesis in mammals is examined. It is pointed out that there are important differences and distinctions between the cellular reactions that 1) couple to oxygen consumption, 2) uncouple metabolism, 3) hydrolyze ATP, 4) control metabolic rate, 5) regulate metabolic rate, 6) produce heat, and 7) dissipate free energy. The quantitative contribution of different cellular reactions to these processes is assessed in mammals. We estimate that similar to 90% of mammalian oxygen consumption in the standardstate is mitochondrial, of which similar to 20% is uncoupled by the mitochondrial proton leak and 80% is coupled to ATP synthesis. The consequences of the significant contribution of proton leak to standard metabolic rate for tissue P-to-O ratio, heat production, and free energydissipation by oxidative phosphorylation and the estimated contribution of ATP-consuming processes to tissue oxygen consumption rate are discussed. Of the 80% of oxygen consumption coupled to ATP synthesis, similar to 25-30% is used by protein synthesis, 19-28% by the Na+-K+-ATPase, 4-8% by the Ca2+-ATPase, 2-8% by the actinomyosin ATPase, 7-10% by gluconeogenesis, and 3% by ureagenesis, with mRNA synthesis and substrate cycling also making significant contributions. The main cellularreactions that uncouple standard energy metabolism are the Na+, K+, H, and Ca2+ channels and leaks of cell membranes and protein breakdown. Cellular metabolic rate is controlled by a number of processes including metabolic demand and substrate supply. The differences in standard metabolic rate between animals of different body mass and phylogeny appear to he due to proportionate changes in the whole of energy metabolism. Heat is produced by some reactions and taken up by others but is mainly produced by the reactions of mitochondrial respiration, oxidative phosphorylation, and proton leak on the inner mitochondrial membrane. Free energy is dissipated by all cellular reactions, but the major contributions are by the ATF-utilizing reactions and the uncoupling reactions. The functions and evolutionary significance of standard metabolic rate are discussed.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 21/09/20 alle ore 12:34:42