Abstract des Autors

The aim of the present study was to test whether similar increments in plasma norepinephrine concentration (NE) induced by exercise or i.v. NE infusion will result in similar increments in plasma norepinephrine sulfate (NE-S). This would support the hypothesis that plasma NE-S at the end of exercise is a cumulative index of NE spillover with exercise. Increments in NE were elicited by 1 h bicycle exercise (BE: 65% VO2max) or by 1 h intravenous infusion of NE under resting conditions (INF; 0.14 micro-g/kg/min). The study was carried out placebo-controlled, randomized, single-blind and crossover with N=11 male subjects (VO2max: 52.5+/-4 ml/kg/min). NE increased similarly with BE and INF compared with resting values (from 2.3+/-0.7 to 13.5+/-1.6 nmol/l and from 2.2+/-0.6 to 14.8+/-2.8 nmol/l, respectively: means+/-S.E.). Plasma NE-S concentration increased similarly with BE (from 5.8+/-1.0 to 8.5+/-1.3 nmol/l) and INF (from 5.7+/-0.8 to 8.9+/-1.0 nmol/l). Heart rate increased from 58+/-2 at rest to 161+/-4 bpm after BE, and decreased from 60+/-3 at rest to 44+/-2 bpm after INF. Data indicate that increments in plasma NE-S primarily depend on increments in plasma NE supporting the hypothesis that plasma NE-S at the end of exercise is a cumulative index of NE spillover with exercise. Verf.-Referat