Search results for " uptake"
showing 10 items of 306 documents
Effect of serotonin uptake inhibition by zimelidine on hypothalamic-pituitary-adrenal activity
1983
Plasma ACTH levels after oral ingestion of 2 g metyrapone at 24.00 hours in six healthy subjects were higher after pretreatment with zimelidine (300 mg) in comparison to placebo. Since zimelidine is a relatively selective serotonin reuptake inhibitor its action on hypothalamic-pituitary-adrenal (HPA) activity suggests that serotonin is a potent stimulator of ACTH release. The ratio of cortisol to 11-deoxycortisol was taken as a measure of 11-hydroxylase activity, which indicates biological activity of secreted ACTH. These cortisol/11-deoxycortisol ratios were significantly increased after zimelidine treatment, when compared to placebo. Both the ACTH response and the cortisol/11-deoxycortiso…
Influence of St John's wort on catecholamine turnover and cardiovascular regulation in humans
2004
BACKGROUND: St John's wort (Hypericum perforatum) is a popular over-the-counter antidepressant. Its antidepressive effect has been attributed in part to inhibition of monoamine transporters and monoamine oxidase, on the basis of in vitro studies. METHODS: In a double-blind, randomized, placebo-controlled, crossover study, 16 healthy subjects (11 men and 5 women; mean age, 31 +/- 5 years) ingested either St John's wort (300 mg three times daily) or placebo for 7 days. Imipramine treatment (50 mg three times daily) in 7 subjects served as a positive control. After treatment, physiologic and biochemical tests included cardiovascular reflex testing, graded head-up tilt testing, and plasma catec…
Comparison of the 45-Second/15-Second Intermittent Running Field Test and the Continuous Treadmill Test
2012
Purposes:To compare the physiological responses and maximal aerobic running velocity (MAV) during an incremental intermittent (45-s run/15-s rest) field test (45-15FIT) vs an incremental continuous treadmill test (TR) and to demonstrate that the MAV obtained during 45-15FIT (MAV45-15) was relevant to elicit a high percentage of maximal oxygen uptake (VO2max) during a 30-s/30-s intermittent training session.Methods:Oxygen uptake (VO2), heart rate (HR), and lactate concentration ([La]) were measured in 20 subjects during 2 maximal incremental tests and four 15-min intermittent tests. The time spent above 90% and 95% VO2max (t90% and t95% VO2max, respectively) was determined.Results:Maximal ph…
Mechanical work and efficiency in ergometer bicycling at aerobic and anaerobic thresholds
1987
Internal and external mechanical work, energy consumption and mechanical efficiency were studied in constant-load ergometer bicycling at five different power outputs below, equal to, and above the aerobic (AerT) and anaerobic (AnT) thresholds. The gross, net and true efficiencies of the whole body in five male subjects were calculated. The work against the external load was defined as the external mechanical work. The internal mechanical work was calculated as the sum of the increments of kinetic and potential energy in all body segments by using methods of film analysis. Total energy consumption was measured by combining aerobic and anaerobic energy production. When the power output of the…
Exercise intolerance at high altitude (5050 m): critical power and W'.
2011
Abstract The relationship between work rate (WR) and its tolerable duration (tLIM) has not been investigated at high altitude (HA). At HA (5050 m) and at sea level (SL), six subjects therefore performed symptom-limited cycle-ergometry: an incremental test (IET) and three constant-WR tests (% of IET WRmax, HA and SL respectively: WR1 70 ± 8%, 74 ± 7%; WR2 86 ± 14%, 88 ± 10%; WR3 105 ± 13%, 104 ± 9%). The power asymptote (CP) and curvature constant (W′) of the hyperbolic WR–tLIM relationship were reduced at HA compared to SL (CP: 81 ± 21 vs. 123 ± 38 W; W′: 7.2 ± 2.9 vs. 13.1 ± 4.3 kJ). HA breathing reserve (estimated maximum voluntary ventilation minus end-exercise ventilation) was also comp…
Enhancement of human cortico-motoneuronal excitability by the selective norepinephrine reuptake inhibitor reboxetine
2002
It has been proposed that norepinephrine plays a critical role in the modulation of cortical excitability, which in turn is thought to influence functional recovery from brain lesions. The purpose of the present experiments was to determine if it is possible to modulate cortical excitability with the selective norepinephrine reuptake inhibitor reboxetine in intact humans. Recruitment curve and intracortical facilitation, assessed by transcranial magnetic stimulation, were increased after oral intake of 8 and 4 mg reboxetine, in the absence of changes in motor threshold, intracortical inhibition, M-response, F-wave or H-reflex. These results demonstrate that reboxetine enhances cortical exci…
A fatal paramethoxymethamphetamine intoxication.
2003
During the last years in Germany a marked increase in the use of amphetamines such as 3,4-methylenedioxymethamphetamine (MDMA, ecstasy) has been observed. The use of these recreational drugs is especially common among young people participating in rave parties. Occasionally ring-methoxylated phenethylamine derivatives like paramethoxymethamphetamine (PMMA) or paramethoxyamphetamine (PMA) are found in street drugs offered as ecstasy. These compounds exhibit a higher toxicity than the methylenedioxyamphetamine derivatives. We report on the death of a 22-year-old man after the ingestion of ecstasy pills containing PMMA and PMA. The PMMA concentration in femoral blood was 0.85 mg/l. Besides PMA…
Neuromuscular and physiological variables evolve independently when running immediately after cycling
2015
International audience; During the early period of running after cycling, EMG patterns of the leg are modified in only some highly trained triathletes. The majority of studies have analysed muscle EMG patterns at arbitrary, predetermined time points. The purpose of this study was to examine changes to EMG patterns of the lower limb at physiologically determined times during the cycle-run transition period to better investigate neuromuscular adaptations. Six highly trained triathletes completed a 10 min isolated run (IR), 30 min of rest, then a 20 min cycling procedure, before a 10 min transition run (C-R). Surface EMG activity of eight lower limb muscles was recorded, normalised and quantif…
Noninvasive Determination of Anaerobic Threshold Based on the Heart Rate Deflection Point in Water Cycling
2015
This study compared heart rate (HR), oxygen uptake (V[Combining Dot Above]O2), percentage of maximal HR (%HRmax), percentage of maximal V[Combining Dot Above]O2, and cadence (Cad) related to the anaerobic threshold (AT) during a water cycling maximal test between heart rate deflection point (HRDP) and ventilatory (VT) methods. In addition, the correlations between both methods were assessed for all variables. The test was performed by 27 men in a cycle ergometer in an aquatic environment. The protocol started at a Cad of 100 b·min-1 for 3 minutes with subsequent increments of 15 b·min-1 every 2 minutes until exhaustion. A paired two-tailed Student's t-test was used to compare the variables …
Effect of pedalling rates on physiological response during endurance cycling
2001
International audience; This study was undertaken to examine the effect of different pedalling cadences upon various physiological responses during endurance cycling exercise. Eight well-trained triathletes cycled three times for 30 min each at an intensity corresponding to 80% of their maximal aerobic power output. The first test was performed at a freely chosen cadence (FCC); two others at FCC-20% and FCC +20%, which corresponded approximately to the range of cadences habitually used by road racing cyclists. The mean (SD) FCC, FCC-20% and FCC + 20% were equal to 86 (4), 69 (3) and 103 (5) rpm respectively. Heart rate (HR), oxygen uptake (VO2), minute ventilation (VE) and respiratory excha…