Modulation of mitochondrial nitric oxide synthase and energy expenditure in rats during cold acclimation

The results presented here indicate that this contribution varies from an ambient to a cold environment

Jorge Guillermo Peralta; Paola V. Finocchietto; Daniela Converso; Francisco Schöpfer; Marı́a Cecilia Carreras; Juan José Poderoso


Scholarcy highlights

  • COLD EXPOSURE IS A STRESSFUL event that elicits different thermogenic adaptive responses in endotherms and exotherms
  • The putative role of mitochondrial NO synthases in cold acclimation was analyzed in the context of the different responses contributing to preservation of thermoneutrality
  • At persistently high caloric intake, heightened metabolic rate was reversed; adaptive thermogenesis with high basal metabolic rate could be prolonged in mice, but the result may be quite variable after some weeks of cold exposure in rats, birds, rabbits, or humans
  • Depending on matrix steady-state concentration, nitric oxide tunes up liver and muscle mitochondrial O2 uptake in vivo and ex vivo through inhibition of cytochrome oxidase; likewise, matrix NO takes part in the modulation and distribution of total BMR
  • ENOS dysfunction has been reported after prolonged cold exposure. These results suggest the importance of mtNOS activity in the different contribution of tissues to total BMR and energy expenditure throughout acclimation
  • If it is considered that 7 mol of ATP are required per mole of synthesized triglyceride, decreased contribution of muscle and liver to BMR should largely account for fat deposition and weight gain in period B; an estimated 25% reduction of caloric availability in the transition from period A to period B is almost one-half of the decrease resulting from mtNOS inhibition of mitochondrial oxidative metabolism

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