Fig. 3.

In vitro measurements of oxygen consumption of isolated brown adipocytes at baseline in presence of selective β2-adrenoreceptor agonist and in presence of norepinephrine. A: oxygen consumption curve of isolated brown adipocytes measured using a Clark-type oxygen electrode. No change in oxygen consumption was observed in presence of increasing doses of salbutamol whereas a marked increase immediately followed addition of norepinephrine in the closed chamber. Black arrows represent addition of 100-μl salbutamol solution at the following concentrations (in g/l): 10⁻⁵, 10⁻⁴, 10⁻³, 0.01, and 0.1 g/ and the dotted arrow represents addition of 100 μl of a 0.01 g/l norepinephrine solution. B: maximal oxygen consumption in isolated brown adipocytes measured at baseline in presence of salbutamol and norepinephrine. **P < 0.01 vs. baseline. Measurement was repeated in 4 sets of cells during each experiment, and 4 independent experiments were performed.