Dataset Information

A comparison between the effects of cold exposure in vivo and of noradrenaline in vitro on the metabolism of the brown fat of new-born rabbits.

ABSTRACT: 1. Exposure of new-born rabbits to the cold leads to an increase in the incorporation of [(14)C]glucose into the glycerol of brown-fat triglyceride, but has no effect on [(14)C]glucose incorporation into triglyceride of white fat or liver. The effect of cold exposure on brown-fat triglyceride is abolished by cutting the cervical sympathetic nerve. 2. Brown fat incorporates very little [(14)C]glucose into triglyceride fatty acids, either in vivo or in vitro. 3. Noradrenaline added to incubations of brown fat from new-born rabbits stimulates O(2) consumption, CO(2) output and incorporation of glucose into triglyceride glycerol. The effects of noradrenaline in vitro are therefore consistent with the hypothesis that noradrenaline mediates the response of the brown fat of new-born rabbits to cold exposure. 4. Glycerokinase is present in the brown fat of new-born rabbits, but its activity is much less than that of the glycerokinase in the brown fat of adult rats. 5. Insulin has no effect on O(2) consumption, CO(2) output or glucose uptake in brown fat of new-born rabbits. 6. It is concluded that the thermogenic response of new-born rabbits to cold exposure is accompanied by a selective acceleration of the triglyceride cycle in brown fat. However, resynthesis of triglyceride would not account for more than 1% of the O(2) consumed in vitro by new-born rabbit brown fat in the presence of noradrenaline if respiration remains coupled to phosphorylation.

SUBMITTER: Knight BL

PROVIDER: S-EPMC1179324 | biostudies-other | 1970 Aug

REPOSITORIES: biostudies-other

ACCESS DATA

Similar Datasets

Project description:INTRODUCTION: Mild cold acclimation is known to increase brown adipose tissue (BAT) activity and cold-induced thermogenesis (CIT) in humans. We here tested the effect of a lifestyle with frequent exposure to extreme cold on BAT and CIT in a Dutch man known as 'the Iceman', who has multiple world records in withstanding extreme cold challenges. Furthermore, his monozygotic twin brother who has a 'normal' sedentary lifestyle without extreme cold exposures was measured. METHODS: The Iceman (subject A) and his brother (subject B) were studied during mild cold (13°C) and thermoneutral conditions (31°C). Measurements included BAT activity and respiratory muscle activity by [18F]FDG-PET/CT imaging and energy expenditure through indirect calorimetry. In addition, body temperatures, cardiovascular parameters, skin perfusion, and thermal sensation and comfort were measured. Finally, we determined polymorphisms for uncoupling protein-1 and ?3-adrenergic receptor. RESULTS: Subjects had comparable BAT activity (A: 1144 SUVtotal and B: 1325 SUVtotal), within the range previously observed in young adult men. They were genotyped with the polymorphism for uncoupling protein-1 (G/G). CIT was relatively high (A: 40.1% and B: 41.9%), but unlike during our previous cold exposure tests in young adult men, here both subjects practiced a g-Tummo like breathing technique, which involves vigorous respiratory muscle activity. This was confirmed by high [18F]FDG-uptake in respiratory muscle. CONCLUSION: No significant differences were found between the two subjects, indicating that a lifestyle with frequent exposures to extreme cold does not seem to affect BAT activity and CIT. In both subjects, BAT was not higher compared to earlier observations, whereas CIT was very high, suggesting that g-Tummo like breathing during cold exposure may cause additional heat production by vigorous isometric respiratory muscle contraction. The results must be interpreted with caution given the low subject number and the fact that both participants practised the g-Tummo like breathing technique.

Dataset Information

A comparison between the effects of cold exposure in vivo and of noradrenaline in vitro on the metabolism of the brown fat of new-born rabbits.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets