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1Département Obésité et Métabolisme, Institut National de la Santé et de la Recherche Médicale, Unité 858, Institut de Médecine Moléculaire de Rangueil; 2Faculté de Médecine de Toulouse Service de Pharmacologie, Centre Hospitalier Universitaire; 3Hôpitaux Purpan et Larrey, Toulouse, France; 4Institut National de la Santé et de la Recherche Médicale, Franco-Czech Laboratory for Clinical Research on Obesity, Prague, Czech Republic; and 5Centre d'Investigation Clinique, Hôpital Pur pan, Toulouse, France
Submitted 12 February 2008 ; accepted in final form 10 June 2008
Involvement of sympathetic nervous system and natriuretic peptides in the control of exercise-induced lipid mobilization was compared in overweight and lean men. Lipid mobilization was determined using local microdialysis during exercise. Subjects performed 35-min exercise bouts at 60% of their maximal oxygen consumption under placebo or after oral tertatolol [a β-adrenergic receptor (AR) antagonist]. Under placebo, exercise increased dialysate glycerol concentration (DGC) in both groups. Phentolamine (
-AR antagonist) potentiated exercise-induced lipolysis in overweight but not in lean subjects; the
2-antilipolytic effect was only functional in overweight men. After tertatolol administration, the DGC increased similarly during exercise no matter which was used probe in both groups. Compared with the control probe under placebo, lipolysis was reduced in lean but not in overweight men treated with the β-AR blocker. Tertatolol reduced plasma nonesterified fatty acids and insulin concentration in both groups at rest. Under placebo or tertatolol, the exercise-induced changes in plasma nonesterified fatty acids, glycerol, and insulin concentrations were similar in both groups. Exercise promoted a higher increase in catecholamine and ANP plasma levels after tertatolol administration. In conclusion, the major finding of our study is that in overweight men, in addition to an increased
2-antilipolytic effect, the lipid mobilization in subcutaneous adipose tissue that persists during exercise under β-blockade is not dependent on catecholamine action. On the basis of correlation findings, it seems to be related to a concomitant exercise-induced rise in plasma ANP when exercise is performed under tertatolol intake and a decrease in plasma insulin.
microdialysis; tertatolol; atrial natriuretic peptide; insulin
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