EFFECT OF TRAINING ON EPINEPHRINE-STIMULATED LIPOLYSIS DETERMINED BY MICRODIALYSIS IN HUMAN ADIPOSE-TISSUE

Trained humans (Tr) have a higher fat oxidation during submaximal phys ical work than sedentary humans (Sed). To investigate whether this ref lects a higher adipose tissue lipolytic sensitivity to catecholamines, we infused epinephrine (0.3 nmol . kg(-1). min(-1)) for 65 min in six athletes and six sedentary young men. Glycerol was measured in arteri al blood, and intercellular glycerol concentrations in abdominal subcu taneous adipose tissue were measured by microdialysis. Adipose tissue blood flow was measured by Xe-133-washout technique. From these measur ements adipose tissue lipolysis was calculated. During epinephrine inf usion intercellular glycerol concentrations were lower, but adipose ti ssue blood flow was higher in trained compared with sedentary subjects (P < 0.05). Glycerol output from subcutaneous tissue (Tr: 604 +/- 322 nmol . 100 g(-1). min(-1); Sed: 689 +/- 203; mean +/- SD) as well as arterial glycerol concentrations (Tr: 129 +/- 36 mu M; Sed: 119 +/- 56 ) did not differ between groups. It is concluded that in intact subcut aneous adipose tissue epinephrine-stimulated blood flow is enhanced, w hereas lipolytic sensitivity to epinephrine is the same in trained com pared with untrained subjects.