Abstract des Autors

To evaluate the effects of endogenously (exercise) and exogenously (recombinant hGH) induced increased human growth hormone (hGH) levels on the anabolic IGF1 system, we investigated 6 male subjects (24.8+/-3.0 yrs) under three randomized conditions: 1. control conditions (C); 2. after 1h cycle ergometer exercise at 60% of max. performance (E); 3. after injection of 4 IU rhGH (I; rhGH, with permission of the local ethic committee). All experiments started at 4 p.m. lasting in total 24h. Blood samples were taken every 20 min from a central venous catheter. Sleep was controlled by EEG. Mean 24h [hGH] were increased during E (2.83+/-0.99 ng/ml) and during rhGH (3-59+/-0.52 ng/ml) when compared to C (0.97+/-0.37 ng/ml). [IGF1] slightly decreased during C and E, but it increased during I (from 171.3+/-51.0 to 2 51.4+/-84.5 ng/ml). BP1 increased after exercise (from 20.7+/-3.8 to 70.1+/-24.7 ng/ml), whereas BP3 was significantly lower during E than during rhGH. Probably as an effect of increased [IGF1], [urea] was lower during rhGH (from 5.0+/-0.4 to 3.2+/-0.5 mmol/l) than during C and E. The systemic IGF1 system is not influenced by exercise induced increased plasma [hGH], but it is strongly stimulated by exogenously achieved high hGH levels. Verf.-Referat