Effect of beta-adrenoceptor stimulation on oxygen consumption and triglyceride/fatty acid cycling after exercise.
The purpose of this study was to characterize the effects of prolonged beta-adrenoceptor stimulation on O2 uptake and triglyceride/fatty acid (TG/FA) cycling during rest with and without previous exercise. Eight men performed two exercise (90 min cycling at 56 +/- 3 (SD)% of maximal O2 uptake, followed by 4.5 h bed rest) and two rest-control experiments. In one rest and one exercise experiment a bolus dose (5 micrograms) of the beta-adrenoceptor agonist isoprenaline was given immediately after exercise, followed by a continuous infusion (20 ng kg-1 min-1), and at the corresponding time in the rest experiment. In the other experiments saline was given instead. The O2 uptake increased in the post-exercise period both with and without beta-stimulation. The total excess post-exercise oxygen consumption (EPOC) was not different between saline (8.1 +/- 1.8 (SE) L) and isoprenaline administration (10.8 +/- 1.8 L, P = 0.40). Also, the total accumulated increase in O2 uptake for the 4.5 h period after isoprenaline infusion was not different between the rest (12.5 +/- 2.0 L) and the exercise experiments (15.2 +/- 1.7 L, P = 0.40). The rate of TG/FA cycling increased after both exercise and isoprenaline treatment, but no interaction effect was found. In conclusion, the increases observed in O2 uptake and the rate of TG/FA cycling during beta-adrenoceptor stimulation were not increased by a previous exercise bout.
Børsheim
E
E
Norwegian University of Sport and Physical Education, Oslo, Norway.
Bahr
R
R
Knardahl
S
S
D000318:Adrenergic beta-Agonists / Q000008:administration & dosage; D000328:Adult; D001642:Bicycling; D001786:Blood Glucose; D004837:Epinephrine / Q000097:blood; D005227:Fatty Acids / Q000097:blood*; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D007328:Insulin / Q000097:blood; D007545:Isoproterenol / Q000008:administration & dosage; D008297:Male; D009638:Norepinephrine / Q000097:blood; D010084:Oxidation-Reduction; D010101:Oxygen Consumption / Q000187:drug effects / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology*; D011943:Receptors, Adrenergic, beta / Q000502:physiology*; D013997:Time Factors; D014280:Triglycerides / Q000097:blood*
D000318:Adrenergic beta-Agonists; D001786:Blood Glucose; D005227:Fatty Acids; D007328:Insulin; D011943:Receptors, Adrenergic, beta; D014280:Triglycerides; D007545:Isoproterenol; D006854:Hydrocortisone; D009638:Norepinephrine; D004837:Epinephrine