 Effect of protein-supplemented fasting on metabolic and hormonal responses to epinephrine infusion in obese subjects.Scheen, André  ; ; Scheen, Myriam et alin Hormone & Metabolic Research (1982), 14(5), 240-5 The present study aimed at investigating the effects of an epinephrine (EPI) intravenous infusion (10 micrograms/min for 30 min) in normal subjects and in obese patients before and after 13 days of ... [more ▼] The present study aimed at investigating the effects of an epinephrine (EPI) intravenous infusion (10 micrograms/min for 30 min) in normal subjects and in obese patients before and after 13 days of protein-supplemented fasting (PSF, 70 g protein/day). Blood glucose, plasma free fatty acids (FFA), lactate, insulin (IRI) and glucagon were determined before, during (15, 30 min) and after (+30 and +60 min) the EPI infusion. 1. When compared to lean control subjects, obese patients exhibited a less marked rise in blood glucose and a more important increase in plasma FFA, EPI infusion decreased IRI plasma levels in normals but not in the obese. Plasma glucagon was lower in the obese under basal conditions and their A cell reactivity to EPI was clearly reduced. 2. Comparison of the results obtained in obese patients before and after PSF revealed that EPI-induced blood glucose rise was not altered despite lower basal values after PSF. Plasma lactate response was impaired, probably because of the depletion in muscle glycogen. Reduction in basal plasma IRI was associated with a significantly higher FFA mobilization. Abnormally low basal EPI-stimulated glucagon concentrations persisted after PSF despite concomitant reductions in blood glucose and plasma IRI. [less ▲] Detailed reference viewed: 7 (0 ULg)Critical analysis of the "anaerobic threshold" during exercise at constant workloads.Scheen, André ; ; in European Journal of Applied Physiology and Occupational Physiology (1981), 46(4), 367-77 The method described by Wasserman for anaerobic threshold (AT) determination, based on the recording of ventilatory parameters, was supported by the simultaneous appearance of hyperlactacidemia and ... [more ▼] The method described by Wasserman for anaerobic threshold (AT) determination, based on the recording of ventilatory parameters, was supported by the simultaneous appearance of hyperlactacidemia and hyperventilation during a standardized incremental work test. Our study aimed at testing the AT in another profile of exercise, viz., during exercises at constant workloads. A homogenous population of 66 healthy subjects performed on a treadmill a total of 100 exercises of 20 min duration at constant workloads (43, 48, 52, 57, 63, and 71% VO2 max). The VO2, V, and venous plasma lactic acid (LA) were determined every minute. LA showed an initial transient increase at 43% VO2 max and a steady-state elevated level above 48% VO2 max. In contrast, the hyperventilation threshold (HVT) was only observed above 57% VO2 max, simultaneously with a delayed steady-state VO2 and with a sustained increase of lactate until the end of exercise. The meaning of the simultaneity of these three events must still be studied. However, the dissociation between both early and steady-state lactate thresholds and HVT is not in keeping with the concept of AT. In these conditions, there is no evidence that HVT necessarily represents an AT, viz., a critical intensity of exercise inducing an insufficient oxygen delivery to the muscles. This conclusion does not imply that the measurement of HVT should be rejected as an empirical test of physical fitness. [less ▲] Detailed reference viewed: 25 (2 ULg)Diminution de la secretion d'adrenaline au cours de la diete hypocalorique protelique chez l'obese.Scheen, André ; ; Scheen, Myriam et alin Annales d'Endocrinologie (1981), 42(6), 531-6 The protein-supplemented fasting induces a progressive but moderate decrease in blood glucose (-26%) and a marked rise in plasma free fatty acids levels (+ 43%). Nevertheless the secretion of epinephrine ... [more ▼] The protein-supplemented fasting induces a progressive but moderate decrease in blood glucose (-26%) and a marked rise in plasma free fatty acids levels (+ 43%). Nevertheless the secretion of epinephrine by the adrenal medulla, as indirectly estimated by the ratio of the basal urinary elimination to the recovery percentage from the urine of an epinephrine infusion, shows a significant decrease (- 36%) during the protein diet. Thus the enhanced lipolysis does not result from an adrenergic overactivity but merely depends upon the marked reduction in the plasma insulin level (- 38%). [less ▲] Detailed reference viewed: 58 (1 ULg)Endurance apres propranolol chez l'homme effectuant un exercice dynamique general.; Scheen, André ; et alin Comptes Rendus des Séances de la Société de Biologie et de ses Filiales (1980), 174(5), 919-24 The effects of a single oral dose of 40 mg propranolol on endurance time and on the maximum oxygen consumption were studied in eight healthy young men. They were running on a motor-driven treadmill (work ... [more ▼] The effects of a single oral dose of 40 mg propranolol on endurance time and on the maximum oxygen consumption were studied in eight healthy young men. They were running on a motor-driven treadmill (work rate from 80 to 150% VO2 max. The VO2 max and endurance time were decreased to an average of 10 and 30% of controls respectively. The relationship between the endurance time and the relative work load (VO2/VO2 max) remained unchanged after beta-adrenoceptor blockade. The reduction of the endurance time following beta-adrenoceptor blockade is a consequence of the reduction of the VO2 max. [less ▲] Detailed reference viewed: 40 (0 ULg)Independance du seuil d'hyperlactacidemie et du seuil d'hyperventilation dans l'exercice rectangulaire chez l'homme.Scheen, André ; ; et alin Comptes Rendus des Séances de la Société de Biologie et de ses Filiales (1980), 174(6), 977-82 During exercises at constant workload, the hyperlactatemia threshold (continuous lactate production during the whole exercise) (48% VO2 max) and the hyperventilation threshold (57% VO2 max) are not ... [more ▼] During exercises at constant workload, the hyperlactatemia threshold (continuous lactate production during the whole exercise) (48% VO2 max) and the hyperventilation threshold (57% VO2 max) are not simultaneous. This finding demonstrates that the hyperventilation threshold could not be regarded as an "anaerobic threshold". [less ▲] Detailed reference viewed: 13 (2 ULg)Perfusion intraveineuse d'adrenaline et adaptation a l'exercice musculaire chez l'homme.Scheen, André ; ; et alin Archives Internationales de Physiologie et de Biochimie (1979), 87(3), 575-84 Eleven normal subjects underwent epinephrine perfusions (1.9; 6.1; 11.8 ng/min) during a short (20 min) and mild (50% VO2 max) exercise. VO2 was not modified by epinephrine perfusion, while heart rate ... [more ▼] Eleven normal subjects underwent epinephrine perfusions (1.9; 6.1; 11.8 ng/min) during a short (20 min) and mild (50% VO2 max) exercise. VO2 was not modified by epinephrine perfusion, while heart rate ventrilation and plasmatic lactate were increased proportionally to epinephrine doses. [less ▲] Detailed reference viewed: 51 (1 ULg)Determinisme de la derive lente de la frequence cardiaque pendant l'exercise musculaire.Cornet, Françoise ; Scheen, André ; et alin Comptes Rendus des Séances de la Société de Biologie et de ses Filiales (1978), 172(3), 569-74 The slow increase in heart rate which is observed in normal man submitted to heavy muscular exercise is due for a part to an activation of orthosympathetic cardiac activity which is blocked by beta ... [more ▼] The slow increase in heart rate which is observed in normal man submitted to heavy muscular exercise is due for a part to an activation of orthosympathetic cardiac activity which is blocked by beta antagonists. It is also explained by direct action of hyperthermia on the heart. [less ▲] Detailed reference viewed: 22 (0 ULg)Diminution de l'hyperventilation d'exercise par le blocage des recepteurs beta-adrenergiquesScheen, André ; ; in Comptes Rendus des Séances de la Société de Biologie et de ses Filiales (1976), 170(1), 220-3 In normal subjects, beta-adrenergic blockage by propranolol or pindolol reduces exercise hyperventilation (40 to 60% VO2 max). Detailed reference viewed: 18 (2 ULg) |
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