Exercise suppression of thermoregulatory thermogenesis in warm- and cold-acclimated rats.
An evaluation was made of the effects of an acute exercise bout on nonshivering thermogenesis (NST) in cold-acclimated rats (4 degrees C for 6 weeks) and shivering thermogenesis in 24 degrees C-acclimated rats (24 degrees C for 6 weeks). Assessment techniques included indirect calorimetry during treadmill running and brown adipose tissue (BAT) mitochondrial guanosine diphosphate (GDP) binding immediately following a treadmill run. Calorimetric results for 24 degrees C-acclimated rats running at 4 degrees C indicated total substitution of shivering thermogenesis by exercise-derived heat. No difference in GDP-binding, an index of BAT nonshivering thermogenic activity, was observed between exercised and nonexercised 24 degrees C-acclimated rats. Calorimetric results for cold-acclimated rats running at 4 degrees C indicated a total suppression in the energy cost associated with NST, exercise-derived heat replacing or substituting for NST. Examining BAT properties in the exercised cold-acclimated rats revealed a significant 40% decrease in BAT mitochondrial GDP-binding. These results suggest that during running, metabolic heat due to the exercise totally replaces shivering in 24 degrees C-acclimated rats and totally replaces BAT nonshivering thermogenesis in cold-acclimated rats.
D000064:Acclimatization; D002001:Adipose Tissue, Brown / Q000378:metabolism; D000818:Animals; D001833:Body Temperature Regulation; D003080:Cold Temperature; D006153:Guanosine Diphosphate / Q000378:metabolism; D008297:Male; D008928:Mitochondria / Q000378:metabolism; D010101:Oxygen Consumption; D005082:Physical Exertion; D051381:Rats; D011919:Rats, Inbred Strains; D012768:Shivering
D006153:Guanosine Diphosphate