Effects of exposure to cold and catecholamines on the respiratory quotient and plasma levels of free fatty acids, glucose and urea in non-acclimated rats.

The reported experiments were carried out on 147 male Wistar rats weighing 325 to 400 g kept on normal diet or fasted for 24 hours. These rats were treated with adrenaline, noradrenaline or propranolol (400 micrograms/kg subcutaneously) or were exposed to a temperature of 15 degrees C for 2 hours before and after propranolol injection (400 micrograms/kg). The metabolic rate (MR), respiratory quotient (RQ) and the levels of free fatty acids (FFA), glucose (G) and urea (U) in the plasma were determined. The conclusion was drawn that none of the determined indices alone is a good indicator of changes in the catabolism of lipids, carbohydrates or proteins. However, in the light of the results, simultaneous determination of all parameters, MR including, can provide an indirect information on the role of different substrates in cold thermogenesis.