Cold adaptation in the rat: increased brown fat peroxisomal beta-oxidation relative to maximal mitochondrial oxidative capacity

J Nedergaard, S Alexson… - American Journal of …, 1980 - journals.physiology.org
J Nedergaard, S Alexson, B Cannon
American Journal of Physiology-Cell Physiology, 1980journals.physiology.org
Brown fat hypertrophy in the rat resulting from cold adaptation is shown here to involve
increased mitochondrial, peroxisomal, and lysosomal enzyme activities. Mitochondrial
activity in homogenates of brown fat was estimated as cytochrome c oxidase. After 4 wk in
the cold (+ 5 C), the total activity was 3-fold higher than in control rats, although the specific
activity was somewhat lower. Peroxisomal activity was followed as cyanide-insensitive
palmitoyl-CoA-dependent NAD+ reduction (palmitoyl-CoA oxidase) and as catalase. The …
Brown fat hypertrophy in the rat resulting from cold adaptation is shown here to involve increased mitochondrial, peroxisomal, and lysosomal enzyme activities. Mitochondrial activity in homogenates of brown fat was estimated as cytochrome c oxidase. After 4 wk in the cold (+5 C), the total activity was 3-fold higher than in control rats, although the specific activity was somewhat lower. Peroxisomal activity was followed as cyanide-insensitive palmitoyl-CoA-dependent NAD+ reduction (palmitoyl-CoA oxidase) and as catalase. The total activity of both palmitoyl-CoA oxidase and catalase was more than 10-fold higher than in controls and the specific activity about 3-fold higher. Acid phosphatase, used as a lysosomal marker, showed a 6-fold higher total activity and almost twice as high specific activity. The relatively greater increase in peroxisomes and lysosomes compared with mitochondria indicates an involvement in thermogenesis also for these organelles.
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