The purpose of this study was to investigate whether the release of endothelin-1 (ET-1), a potent vasoconstrictor peptide produced by vascular endothelial cells, is induced by exercise. Venous plasma concentrations of ET-1 were measured by sandwich-enzyme immunoassay before and after endurance exercise with a cycle ergometer at different intensities. Male ...

The microcirculation as a blood reservoir for volume compensation and the microvascular volume change (MVC) as a means of blood volume regulation are investigated. The density equations of LaForte et al. [Am. J. Physiol. 262 (Heart Circ. Physiol. 31): H190-H199, 1992] are modified to assess the MVC and volume of ...

OBJECTIVES: The aim of this study was to evaluate cardiovascular responsiveness after isotonic exercise in cirrhotic patients. METHODS: Included were 11 cirrhotic patients and 10 age-matched normal subjects, who served as controls. Hemodynamic data were obtained on each subject before and after muscle exercise on a treadmill (7 metabolic units). ...

The concentration of endothelin-1 in forearm venous plasma was measured in 10 healthy men at rest and during ergometer bicycling at 65% of maximal aerobic capacity until exhaustion (96 +/- 10 min, mean +/- SE). A control group of 10 comparable subjects rested for 2 h. Mean plasma endothelin-1 concentration ...

The present study investigated the effect of concentric exercise on cytokine plasma levels and cytokine pre-mRNA in blood mononuclear cells (BMNCs). Healthy young moderately trained men performed ergometer bicycle exercise for 1 h at 75% of maximal oxygen uptake. The levels of plasma interleukin (IL)-6 increased significantly during exercise, but ...

In general, the small number of haemorrheological studies concerning acute changes in long term exercise reveals remarkable small effects, given the substantial changes of pertinent cardiorespiratory parameters. To a large extent, this appears to result from careful maintenance of extra- and intravascular water balance and adequate control of electrolytes. Haemorrheological ...

Cardiovascular drugs have varying effects on hemodynamic, metabolic, and hormonal responses to exercise. To evaluate the effects of the novel angiotensin-converting enzyme (ACE) inhibitor, perindopril on these exercise-related responses, we studied 9 healthy volunteers in a double-blind, randomized, placebo-controlled trial. After a week of perindopril 4 mg orally daily or ...

This study compared plasma volume (PV) and ion regulation during prolonged exercise in control vs. glycogen-depleted (GD) conditions, with emphasis on the initial minutes of exercise. In two trials separated by 1-2 wk, four adult males cycled at 75% of peak oxygen consumption (VO2) until exhaustion (50 +/- 7 min ...

1. In postganglionic sympathetic neurones and adrenal chromaffin cells, catecholamines are co-stored in vesicles with soluble peptides, including chromogranin A (CgA) and neuropeptide Y (NPY), which are subject to exocytotic co-release with catecholamines. 2. Plasma catecholamine, CgA and NPY responses to stimulators and inhibitors of sympatho-adrenal catecholamine storage and release ...

The aim of this study was 1) to establish the relationship between testosterone (T) levels and the intensity and duration of exercise in conscious dogs, and 2) to investigate the involvement of the sympathetic system in the response of plasma T to acute exercise. The experiments were performed on 14 ...

Neuropeptide Y (NPY) has been recently characterised as a circulating vasoconstrictor peptide which is co-stored with noradrenaline (NA) in sympathetic neurons. We measured NPY by radioimmunoassay and NA by HPLC in plasma of ten healthy volunteers (23-27 years of age) during bicycle ergometry and found a rapid increase of both ...

Twenty-two male soccer players (mean age 21.3 yrs) performed an incremental, multistage bicycle ergometer exercise test with work load increasing by 50 W, until volitional exhaustion. The exercise stages lasted 3 min and were separated by 1 min resting periods. Before exercise and during each load an audio-visual five-choice reaction ...

Forty-two patients with congestive heart failure were studied in order to clarify whether the plasma level of neuropeptide Y-like immunoreactivity (NPY-LI) rises in parallel with plasma noradrenaline (NA) during physical exercise in congestive heart failure (CHF). All patients were studied in a randomized placebo-controlled trial with the ACE-inhibitor ramipril during ...

Plasma norepinephrine (NE), epinephrine (E), and neuropeptide Y (NPY) were evaluated in seven young (median age 29 yr, range 21-31) and seven elderly (median age 61 yr, range 51-72) healthy subjects. They were all nonsmokers and had never smoked. Basal values and the initial increase in plasma NE and E ...

In a previous study we showed, in both asthmatic patients and in healthy subjects, a marked increase in plasma concentration of nedocromil immediately following an exercise challenge with associated FEV1 measurements. To identify which component of the exercise challenge is responsible, we have now studied the effect of various manoeuvres ...

This study examined the effect of dynamic exercise on vasopressin release in the miniswine and factors that may elicit this response (n = 15). Thus lysine vasopressin (LVP), the catecholamines epinephrine and norepinephrine (EPI and NE), plasma renin activity (PRA), and plasma volume, Na+, and osmolality were measured before and ...

A single blind cross-over study was performed comparing a new microencapsulated potassium chloride tablet (MET) with two reference formulations of oral potassium, namely potassium chloride solution (PS), and microencapsulated potassium chloride capsules (MEC), in 18 normal healthy volunteers. The potassium chloride induced change in gastric potential difference (PD) of the ...

The exercise- and drug-induced potassium shifts in pregnant women was studied. Six healthy nonpregnant women, six healthy pregnant women and four hypertensive, pregnant women on labetalol performed a bicycle exercise test. Blood samples for plasma potassium concentrations were drawn before, during and after the exercise. The exercise-induced plasma potassium increase ...

The plasma total biopterin and tetrahydrobiopterin levels of 29 normal volunteers were measured before and after exercise by ergometer, and those of 10 were also measured until 24 h after exercise. An increase of plasma total biopterin and tetrahydrobiopterin was observed only after strong exercise, which exhausted the subjects, the ...

This investigation examined the influence of pre-exercise hydration status, and water intake during low intensity exercise (5.6 km.h-1 at 5% gradient) in the heat (33 degrees C), on plasma testosterone (TEST), cortisol (CORT), adrenaline (A), and noradrenaline (NA) concentrations at baseline (BL), pre-exercise (PRE), and immediately (IP), 24 h (24 ...

Adenine nucleotide (AN) degradation has been shown to occur during intense exercise in man and in the horse, at or close to the point of fatigue. The aim of the study was to compare plasma ammonia concentration ([NH3]) as a result of intense exercise with plasma [lactate]. Plasma glutamine concentration ...

Basal venous plasma noradrenaline and muscle sympathetic nervous activity both increase with age. It has been reported that during exercise venous plasma noradrenaline increased more in elderly subjects both at the same relative as well as the same absolute work load, compared to younger subjects. Recent studies have shown that ...

The present study was undertaken in order to establish the possible involvement of GABAergic and/or opioid pathways in the mechanism underlying the arginine-vasopressin (AVP) response to physical exercise. After fasting overnight, seven subjects were tested on four mornings at least 1 week apart. Exercise was performed on a bicycle ergometer. ...

1. Catechol-O-methyltransferase (COMT) inhibition might be assumed to potentiate the effects of circulating catecholamines, particularly under conditions of enhanced catecholamine release. 2. The purpose of the present study was to establish whether the novel COMT inhibitor, entacapone, changes haemodynamic responses and catecholamine metabolism during exercise. 3. Entacapone was given orally ...

Plasma free fatty acid (FFA) levels tend to be lower and the plasma lipolytic hormone response to prolonged exercise of the same intensity is blunted after endurance exercise training. To determine whether training elicits a corresponding decrease in plasma FFA turnover and metabolism during prolonged exercise, we measured plasma [1-13C]palmitate ...

The proportionality which in general exists between rates of sympathetic nerve firing and the overflow of noradrenaline into the venous drainage of an organ provides the experimental justification for the use of measurements of noradrenaline in plasma as a biochemical measure of sympathetic nervous function. Static measurements of noradrenaline plasma ...

Eosinophil cationic protein (ECP) has been shown to be a marker of eosinophil granulocyte activation. In 10 healthy young subjects the plasma concentrations of ECP were measured before and after a graded maximal bicycle exercise test. The analyses were carried out 30 min before and immediately before exercise, immediately after ...

1. The effects of hypohydration produced by 48 hr water deprivation were examined in dogs during moderate treadmill exercise at an ambient temperature (Ta) of 21 degrees C. 2. Hypohydration caused a significant elevation in plasma levels of adrenaline (A), proteins (pp) and osmolality (pOsm). 3. During 1 hr of ...

Fibrinogen can be considered as a major cardiovascular risk factor. Therefore there is a growing interest in methods to lower its plasma level. This paper is aimed at reviewing the data investigating the effects of regular exercise on plasma fibrinogen levels. Cross-sectional studies strongly suggest that regular exercise will reduce ...

The present study was designed to determine the cumulative effects of a series of four resistive exercises on intravascular plasma volume throughout one exercise session. Seven healthy males, mean (+/- SE) age 26.7 +/- 1.2 y, participated in the study. In two separate trials the subjects' one-repetition maximum (1-RM) and ...

The purpose of this study was to test the hypothesis that furosemide administration before exercise would cause greater increases in plasma arginine vasopressin (AVP) concentration in exercising horses than exercise alone. Six adult, clinically normal, unfit mares underwent three randomly ordered 60 minute standard exercise tests on an equine treadmill ...

To test the hypothesis that marathon running is dependent on lipid oxidation, 12 post-absorptive males (31.9 +/- 2.1 yr) ran a treadmill marathon and substrate utilization was assessed. Subjects were placed into a fast (F < or = 2 hr, 45 min; 73.3% VO2max), or a slow (S < or ...

The dynamics of change in plasma volume (PV) and baroreflex responses have been reported over 24 h immediately following maximal cycle exercise. The purpose of this study was to determine if PV and baroreflex showed similar changes for 24 h after resistance exercise. Eight men were studied on 2 test ...

Nine adult female sheep were each surgically fitted with an Ivan and Johnston reentrant cannula in the cranial part of the duodenum just distal to the pylorus. By diversion (loss) of abomasal outflow, this model has been shown to consistently induce hypochloremic, hypokalemic metabolic alkalosis, accompanied by hyponatremia and dehydration. ...

This study examined the effects of branched-chain amino acid (BCAA) supplementation on amino acid and ammonia (NH3) responses during prolonged exercise in humans. Seven men cycled for 60 min at 75% of maximal O2 uptake after 45 min of either placebo (dextrose, 77 mg/kg) or BCAA (leucine + isoleucine + ...

Changes in plasma magnesium (Mg) and other cations in response to exercise have been previously reported, but whether ingestion of fluids providing carbohydrate and electrolytes modifies the changes has not been determined. We examined patterns of change in plasma Mg, calcium (Ca), sodium (Na), and potassium (K) in 10 men ...

To investigate the effect of short-term training on Na(+)-K(+)-adenosine triphosphatase (ATPase) concentration in skeletal muscle and on plasma K+ homeostasis during exercise, 9 subjects performed cycle exercise for 2 h per day for 6 consecutive days at 65% of maximal aerobic power (VO2 max). Na(+)-K(+)-ATPase concentration determined from biopsies obtained ...

Six intact and 6 splenectomised mares were given an incremental exercise test on a treadmill to examine the fluid and electrolyte changes associated with exercise and the role of the spleen in these changes. Blood samples were obtained at rest and at the end of each 1-min step of the ...

We investigated the role of the exercise-induced elevation of plasma prolactin (PRL) concentration on sweat rate and composition during prolonged exercise in men. Two groups of healthy young males (20-26 yr old) showing a high (high responders; n = 8) or a low (low responders; n = 7) response of ...

Blood levels of intermediary metabolites were measured and indirect calorimetry was performed in 10 otherwise healthy, non-insulin-dependent diabetic (NIDDM) patients before, during, and after 30 minutes of moderate exercise on three occasions in random order at weekly intervals with (1) heparin treatment to increase preexercise plasma nonesterified fatty acid (NEFA) ...

Lower body negative pressure (LBNP) is a stimulus frequently used to study reflex circulatory responses in humans. Studies have provided data on LBNP-induced blood pooling; however, the possibility that LBNP also might be associated with an important loss of plasma fluid has attracted little attention. Therefore this problem was analysed ...

Physical exercise leads to many metabolic, cardiovascular, and muscular changes in the body. The trace elements (TE) zinc and copper are directly involved, as enzymatic cofactors, in many of these processes, especially those related to nutrients metabolism, oxygen transport, and formation of usable energy. The effects of high-intensity physical exercise ...

The aim of the present study was to verify whether a single oral dose of methylprednisolone could modulate the exercise-induced release of polymorphonuclear neutrophil (PMN) elastase and myeloperoxidase. Four healthy, male subjects were submitted to a 20 min downhill run (-20%) at 60% VO(2) max, 3 h after oral absorption ...

An investigation was carried out on the effect of lecithin (phosphatidylcholine, 90%) on the plasma choline concentrations during continuous strain in 10 top level triathletes (4 women and 6 men), trial I, and 13 excellent adolescent runners (3 girls and 10 boys), trial II. Venous blood, collected before and immediately ...

We investigated the response of plasma and platelet:free catecholamine ([CA]) and sulphated catecholamine ([CA-S]) concentrations after an incremental treadmill test to exhaustion and during recovery. In triathletes (n = 9) plasma and platelet [CA] and [CA-S] were measured before, immediately after and 0.5 and 24 h after exercise. In long-distance ...

The purpose of this study was to determine if fluid-electrolyte, renal, hormonal, and cardiovascular responses during and after multi-hour water immersion were associated with aerobic training. Additionally, we compared these responses in those who trained in a hypogravic versus a 1-g environment. Seventeen men comprised three similarly aged groups: six ...

Eight endurance trained distance runners (5 male and 3 female) ran on a treadmill at 60% of their VO2max for 3 h. Blood samples (about 12 ml) were taken immediately prior to the exercise, and thereafter every 30 min during and at the end of exercise. Urinary urea excretion was ...

Alterations of acid-base status, and fluid and electrolyte balance subsequent to exercise in Thoroughbred racehorses in North America have not been well-characterized. Des-cribed here are the results of an observational study conducted to characterize changes in fluid and electrolytes following strenuous exercise of 16 Thoroughbreds under routine training conditions. Changes ...

This investigation evaluated the influence of metabolic alkalosis on plasma ammonia (NH3) accumulation during incremental exercise. On two occasions separated by at least 6 days, six healthy men cycled at 70, 80, and 90% of maximum oxygen consumption (VO2max) for 5 min; each exercise period was followed by 5 min ...

To elucidate the role of factors other than the nervous system in heart rate (fc) control during exercise, the kinetics of fc and plasma catecholamine concentrations were studied in ten heart transplant recipients during and after 10-min cycle ergometer exercise at 50 W. The fc did not increase at the ...