Cellular energy utilization and molecular origin of standard metabolic rate in mammals

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