Studies on Plasma Free-Fatty-Acid Metabolism and Triglyceride Synthesis of Brown Adipose Tissue in vivo during Cold-Induced Thermogenesis of the Newborn Rabbit.

Parameters of plasma free fatty acid metabolism (pool size, half time, disappearance rate, turnover time and absolute turnover rate), the influx of plasma free fatty acids into the glycerides of brown adipose tissue and the pathway of triglyceride synthesis in brown adipose tissue (glycerol-1-phosphate versus monoglyceride pathway) were examined after intravenous injection of [1-¹⁴C]palmitate in newborn rabbits. In the thermoneutral environment of 35 °C the turnover rate of plasma free fatty acids was 10.20 µmol/min per 100 g body weight and its flux into the glycerides of brown adipose tissue 0.367 µmol/min per 100 g body weight. Cold exposure at an ambient temperature of 20 °C caused a decrease to 5.84 µmol/min and 0.207 µmol/min per 100 g body weight, respectively. Both under basal conditions at an ambient temperature of 35 °C and under cold-induced thermogenesis at an ambient temperature of 20 °C triglyceride synthesis in brown adipose tissue ran through the glycerol 1-phosphate pathway. [ABSTRACT FROM AUTHOR]