Figure 3
C12TPP-stimulated oxygen consumption in brown-fat mitochondria and brown adipocytes isolated from wild-type and UCP1-KO mice. Representative trace depicting titration with C12TPP of brown-fat mitochondria from wild-type (a) or UCP1-KO (b) mice. C12TPP was successively added at concentrations ranging from 11 to 44 μM (the concentration was increased by 11 μM in each step). Additions were 5 mM pyruvate (Pyr), 1 mM GDP and 2.1 μM carbonyl cyanide p-(trifluoromethoxy) phenylhydrazone (FCCP). (c) Comparison of the effects of C12TPP in wild-type and UCP1-KO brown-fat mitochondria. The mitochondria were examined as shown in a and b, and the values were obtained by estimating the maximal responses. The mean and individual data points of four to six independent mitochondrial preparations for each group are presented. Representative traces depicting the oxygen consumption of control (d) and C12TPP-pretreated (e) brown adipocytes. Primary cultures of brown adipocytes were treated with 0.1% ethanol (control) or 1 μM C12TPP for 3 h before harvesting. Additions were 1 μM β-adrenergic agonist norepinephrine (NE), 2 μM oligomycin and 60 μM FCCP. C12TPP effects on oxygen consumption rates in brown adipocytes originating from wild-type mice (f) or UCP1-ablated mice (g). Control and C12TPP-treated adipocytes were examined in parallel as shown in d and e. The oxygen consumption rate of control adipocytes on a given day was defined as 100% and oxygen consumption rate of C12TPP-treated adipocytes from parallel examination is expressed relative to that of these control adipocytes (as % of basal, NE, oligomycin and FCCP). The bars represent the means±s.e.m. of five independent cell cultures of each genotype. The raw data were analyzed with Student’s t-test and asterisks indicate significant differences between control and C12TPP-treated cells.
