| Outcome Measures: |
Primary: Change in Brown Adipose Tissue thermogenesis (formoterol induced, cold-induced and effect of nicotinic acid), determined using \[11C\]-acetate PET, measured 60 minutes before and 90 minutes after cold exposure (A) and 30 minutes after inhalation of Fumarate Formoterol (B and C) | Secondary: Brown Adipose Tissue (BAT) glucose uptake, determined using \[18F\]-FDG dynamic PET acquisition, measured 150 minutes after the start of acute cold exposure (A), and 90 minutes after inhalation of Fumarate Formoterol (B and C)|Brown Adipose Tissue nonesterified fatty acid (NEFA) metabolism (uptake, oxidation, esterification and release rates), determined using \[11C\]-palmitate PET method, measured 120 minutes after the start of acute cold exposure (A), and 60 minutes after inhalation of Fumarate Formoterol (B and C)|Change in systemic plasma NEFA turnover., Determined using continuous infusion of labelled palmitate from time -60 to 180., measured at baseline and every 60 minutes after the start of acute cold exposure (A) and every 60 minutes after inhalation of fumarate formoterol (B and C), for 4 hours|Change in systemic plasma glycerol turnover., Determined using continuous infusion of \[1,1,2,3,3-D2\]-glycerol from time -60 to 180 ., measured at baseline and every hour after the start of acute cold exposure (A) and every hour after inhalation of fumarate formoterol (B and C), for 4 hours.|Change in systemic plasma glucose turnover., Determined using continuous infusion of \[6,6 D2\]-glucose from time -150 to 180 ., measured at baseline and every hour after the start of acute cold exposure (A) and every hour after inhalation of fumarate formoterol (B and C), for 5.50 hours|BAT triglyceride content, Determined using the CT radio-density method, measured 180 minutes after the start of cold exposure (A) and 90 minutes after inhalation of fumarate formoterol (B and C)|Change in whole-body energy expenditure, Determined using indirect calorimetry, measured at baseline and every hour after the start of acute cold exposure (A) and every hour after inhalation of fumarate formoterol (B and C), for 4 hours|Muscle shivering activity, Determined using the surface electromyogram (EMG), measured at baseline and every hour after the start of acute cold exposure (A) and every hour after inhalation of fumarate formoterol (B and C), for 4 hours|Change in insulin sensitivity, Determined by measuring circulating glucose, NEFA, insulin and C-peptide, measured at baseline and every 60 minutes after the start of acute cold exposure (A) and every 60 minutes after inhalation of fumarate formoterol (B and C), for 4 hours.|Protein expression of subcutaneous abdominal white adipose tissue, Using biopsy, measured at baseline and 180 minutes after the start of the cold exposure (study A) and 120 minutes after inhalation of fumarate formoterol (study B and C)
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