Zusammenfassung

1) Role of the adrenergic system in the adaptive changes following physical training. Chronic treatment with ß-adrenergic agonists in animals induces biochemical, structural and physiological changes in skeletal muscle and adipose tissue, and an increase in insulin sensitivity in skeletal muscle that are comparable to those observed physical training, whereas chronic treatment with ß-adrenergic antagonists reduces the metabolic adaptations to exercice training.
2) We want to characterize the ß-adrenergic receptor subtypes present in the three differencr muscle fiber types in rats and in humans. Attempts will be made to characterize and clone the atypical skeletal muscle ß-adrenoceptors.
3)Leptin is a new hormone secreted by the adipocyte and considered as a signal between body fat mass, the control of food intake and thermogenesis. We would like to characterize the possible link between physical exercice, endurance training and leptin expression in rats. Characterization of the ß-adrenergic receptor subtypes mediating catecholamine effects in skeletal muscle and determination of the effects of physical training on these receptors and on leptin production might help design appropriate training programs.

(Zwischen)Ergebnisse

Administration of a ß-blocker (timolol) before a 30 min. constant workload exercise bout in man decreases (slows) VO2 on. The ß-adrenoceptor subtypes in various skeletal muscles of the rat have been identified: the consist in ß2- and two atypical ß-adrenoceptors. Endurance training in rats does not induce a down regulation of skeletal muscle ß2-adrenoceptors. It decreases leptin expression in white adipose tissue and leptin secretion.