beta(1)- and beta(2)-Adrenoceptor-mediated thermogenesis and lipid utilization in obese and lean men.

The aim of this study was to elucidate the roles of theβ 1- and the β2-adrenoceptors in thermogenesis and lipid utilization in obesity. Theβ 1-adrenoceptor study was performed in 9 obese and 10 lean men and consisted of 4 30-min periods during which subjects received consecutive infusions of 0, 3, 6, and 9 μg/kg fat-free mass (FFM)·min dobutamine. Energy expenditure, lipid oxidation, and plasma nonesterified fatty acids and glycerol concentrations increased similarly in both groups during β1-adrenergic stimulation. The β2-adrenoceptor study was performed in 10 obese and 11 lean men and involved 3 45-min periods during which 0, 50, and 100 ng/kg FFM·min salbutamol were given in combination 1.2μ g/kg FFM·min atenolol (bolus, 50 μg/kg FFM). Duringβ 2-adrenergic stimulation, the increases in energy expenditure and plasma nonesterified fatty acids and glycerol concentrations were reduced in the obese group. Furthermore, lipid oxidation significantly increased in the normal weight group, but remained similar in...