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Results 451 - 500 of 1165
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Kane D W - - 1994
We studied the effects of inhibition of nitric oxide (NO) (endothelium-derived relaxation factor) synthase in combination with alpha and beta adrenergic receptor blockade on pulmonary vascular tone during exercise. In paired studies, we exercised sheep on a treadmill at a speed of 4 mph, and measured blood flow and pressures ...
Bellissant E - - 1994
The effects of single oral doses of dilevalol 400 mg and propranolol 80 mg on systemic and regional haemodynamics at rest and after sub-maximal exercise, were compared, in a placebo-controlled, randomised, double-blind, crossover study in 6 healthy male volunteers. At rest, as compared to placebo, neither dilevalol nor propranolol significantly ...
Volz-Zang C - - 1994
The effects of esmolol at different rates of infusion (100, 250 and 500 micrograms.kg-1 BW.min-1) were compared with beta-adrenoceptor occupancy (beta 1 and beta 2, estimated by a subtype selective radioreceptor assay) and plasma concentrations of esmolol and its acid metabolite were measured by HPLC. Up to a rate of ...
Pierce E F - - 1993
Considerable research has shown significant increases in beta-endorphin levels after aerobic activity. These increases and their accompanying euphoric effect have been suggested as a possible psychophysiological mechanism underlying the exercise-dependence syndrome. The relationship between plasma beta-endorphin levels and a tendency towards exercise dependence, however, has not been established. To examine ...
Young R F - - 1993
The authors systematically studied the release of the endogenous opioid peptides beta-endorphin and methionine (met)-enkephalin into the cerebrospinal fluid (CSF) during deep brain stimulation in patients suffering from otherwise intractable chronic pain. Nine patients were included in the study; six had stimulation electrodes placed in both the periventricular gray matter ...
Pierce E F - - 1993
Previous research investigating the response of plasma beta-endorphins (beta-EP) to resistance exercise has resulted in equivocal findings. To further examine the effects of resistance exercise on beta-endorphin immunoreactivity, six resistance-trained athletes participated in a three-set series of eight repetitions of isotonic exercise. All exercises were performed at 80% maximal effort. ...
Gullestad L - - 1993
The role of beta-adrenoceptors in exercise-induced muscle hyperaemia was investigated. Exercise was performed with a small and a large muscle mass: knee extension (KE) and bicycle exercise (BE). Seven healthy subjects performed light and maximal KE and eight subjects performed stepwise dynamic BE to exhaustion before and after acute i.v. ...
Zhuang J - - 1993
To test the hypothesis that native high-altitude residents have less beta-sympathetic and more parasympathetic tone than newcomers, we compared the effects of beta-sympathetic and parasympathetic blockade in 10 Tibetan and 9 Han acclimatized male residents of Lhasa, Tibet Autonomous Region, China (elevation 3,658 m). Each subject was studied during cycle ...
Lemini C - - 1993
The syntheses and characterizations of two new 17 beta-aminoestrogens, butolame [17 beta-(4-hydroxy-1-butylamino)-1,3,5(10)-estratrien-3-ol] and pentolame [17 beta-(5-hydroxy-1-pentylamino)-1,3,5(10)-estratrien-3-ol], are presented. Both compounds, when administered in single subcutaneous injections to male mice and rats, produce dose-dependent increases in blood clotting times that may last several days. The estrogenic effects assessed by the vaginal ...
Aravich P F - - 1993
Exercise and the endogenous opioids have been linked to anorexia nervosa. This investigation determined the effects of the weight-loss syndrome induced by voluntary exercise (22.5 h/day) in food-restricted rats (1.5 h/day food access) on the endogenous opioids. The animals were tested under resting-fed and 2-deoxy-D-glucose (2DG) stimulated conditions. Weight-matched, freely ...
Hanem S - - 1993
Stimulation of myocardial alpha 1-adrenoceptors mediates changes in potassium fluxes across the sarcolemma. We studied the effect of alpha 1-adrenoceptor stimulation (5 x 10(-5) M phenylephrine with addition of 10(-6) M timolol) on potassium efflux by use of 86Rb+ efflux from isolated rat hearts perfused in a nonrecirculation system. The ...
Harris A - - 1993
Acute mild exercise accelerates transit of material through the gastrointestinal tract via mechanisms that remain entirely unknown. Because exercise increases peripheral sympathetic drive, and can increase circulating opioids, in this study we examined the role that naloxone and propranolol-dependent pathways play in accelerating orocecal transit in exercise. Transit was determined ...
Akhlaghi S - - 1993
This paper reports on a randomized double-blind crossover study to compare the effects of daily treatment with 100 mg conventional metoprolol (M100), 50 or 100 mg slow-release metoprolol CR (CR50, CR100) and placebo on the response to treadmill walking exercise in 12 healthy volunteers. Twenty minutes of exercise was undertaken ...
Yonga G O - - 1993
Possession of beta-1-selectivity and intrinsic sympathomimetic activity (ISA) by beta-adrenergic blocking drugs have been found to modify the effects of these drugs on heart rate, blood pressure and pulmonary airway resistance both at rest and during exercise. In a randomised, double-blind, cross-over, placebo-controlled trial, 21 healthy male volunteers took placebo, ...
Miller P F - - 1993
We compared symptomatic, hemodynamic and opioid responses of heart disease patients to exercise testing and a stressful public speaking task. Plasma beta-endorphins were measured at rest and immediately post stress. Nineteen of 50 patients had angina during exercise; 31 had asymptomatic ischemia. No patient had angina during the speech, but ...
Yonga G O - - 1993
Beta-blockers that are non-selective, beta-1-selective or possess intrinsic sympathomimetic activity (ISA) are thought to differ in their effects on serum potassium, glucose and lactate during exercise. In a randomized, double-blind, cross-over, placebo-controlled study, 21 healthy male volunteers took placebo, propranolol, pindolol and metoprolol on separate occasions. They were subsequently exercised ...
Cohen-Solal A - - 1993
The effects of beta-blockers and calcium-channel blockers on cardiopulmonary response during exercise are not well characterized. Sixteen sedentary patients with essential hypertension underwent a randomized, double-blind, cross-over study comparing atenolol and diltiazem sustained-release 300 mg, each administered during 6 weeks, after a 15-day run-in placebo period. Neither atenolol nor diltiazem ...
Martin W H WH - - 1993
Although thyroid hormone excess results in increased beta-adrenergic receptor density or agonist responses in some cells of experimental animals, the role of these effects in contributing to clinical manifestations of hyperthyroidism in human subjects is unclear. To shed further light on this issue, we characterized the effect of 2 weeks ...
Walley T - - 1993
1. Dilevalol (R,R-labetalol) is a non-selective beta-adrenoceptor antagonist with beta 2-adrenoceptor agonist activity. Its effects after 1 month's administration on heart rate, blood pressure and muscle blood flow were studied in a double-blind crossover comparison with nifedipine in 16 hypertensive patients. 2. Dilevalol and nifedipine were similarly effective in lowering ...
Jensen-Urstad M - - 1993
To investigate the differences in metabolic response between arm exercise (AE) and leg exercise (LE) and to elucidate the underlying mechanisms, seven men were studied during 20 min of AE or LE both with (beta) and without (control, C) nonselective beta-blockade (beta B) (propranolol). The work loads corresponded to 59 ...
Kane D W - - 1993
In paired experiments, we exercised sheep at a constant rate of 4 mph on a treadmill and measured the hemodynamic effects of alpha receptor blockade (phentolamine 5 mg intravenously), beta receptor blockade (propranolol 1 mg intravenously), and combined alpha and beta receptor blockade. Beta blockade increased pulmonary vascular resistance (PVR) ...
Braun U - - 1993
We investigated the counterregulatory effect of the oculocardiac reflex (OCR) in 25 infants and children during strabismus surgery under three experimental conditions. In group 1, a series of measurements were recorded when the OCR was elicited by traction. The beat-to-beat heart rate reduction ranged from -26 to -64 beats/min (median: ...
McGowan R W - - 1993
Research examining the relationship between beta-endorphin immunoreactivity and affect has resulted in equivocal findings. To examine this relationship further, 10 male and 10 female college-age students participated in a controlled free-weight exercise session. Blood plasma samples were procured both prior to and following the exercise bout and beta-endorphin levels were ...
Carpéné C - - 1993
The beta-3 adrenoceptor protein lacks most of the potential phosphorylation sites for beta adrenoceptor kinase and protein kinase A. In addition, it exhibits a lower affinity toward norepinephrine than beta-1 or beta-2 adrenoceptors. It is thus expected that beta-3 adrenoceptors could be less implicated in desensitization processes than the beta-1 ...
Yasuda S U - - 1993
d-Sotalol was developed as an antiarrhythmic agent with a relative lack of antagonist activity at beta-adrenergic receptors. Exercise heart rate reduction has been observed after administration to humans. The purpose of this study was to determine directly whether this effect of d-sotalol was attributable to beta-blockade. Plasma samples from normal ...
Tsuboi M - - 1993
The mechanism underlying exhaustive exercise-induced release of lysosomal enzymes was studied in the rat liver. Exhaustive exercise resulted in the release of beta-glucuronidase and cathepsin D, but not beta-glucosidase and acid phosphatase, into the blood and cytosol, suggesting that the release of lysosomal enzymes is not due to disruption of ...
Pilhall M - - 1993
Changes in the QRS complex during exercise may provide information with respect to ischaemic heart disease. The intention with present investigation was to shed light on mechanisms behind QRS changes and to study the possibly confounding effects of beta-blockade on such alterations with exercise. Placebo or propranolol respectively was infused ...
Takayama S - - 1993
We investigated the chronotropic and inotropic responses to BRL 37344 (a beta 3-adrenoceptor agonist) and isoproterenol in isolated, blood-perfused dog atria. BRL 37344 (0.1-30 nmol) or isoproterenol (0.001-0.3 nmol) increased the sinus rate and contractile force dose dependently. BRL 37344 was 290 times less potent than isoproterenol to increase sinus ...
Townend J N - - 1993
To determine the effect of ACE inhibitor therapy on lymphocyte beta-adrenoceptor function and density, as well as the in vivo myocardial response to beta-agonist stimulation, we studied 12 patients with chronic severe heart failure before and after 16 weeks' treatment with quinapril. Lymphocyte beta-adrenoceptor function (intracellular cAMP production in response ...
Clapp J F JF - - 1993
OBJECTIVE: Our purpose was to test the hypothesis that sustained exercise elevates circulating levels of 17 beta-estradiol in an intensity-dependent manner. STUDY DESIGN: Blood samples were obtained in the follicular phase of the menstrual cycle from 75 female recreational athletes before and immediately after 20 minutes of aerobics or running ...
Gardner M J - - 1993
INTRODUCTION: Left-sided stellate ganglion predominance has been proposed as a mechanism responsible for lethal ventricular arrhythmias, due to heterogenous ventricular repolarization. To determine the cardiovascular effects of such asymmetric sympathetic ganglion innervation in man, studies were performed in 15 patients undergoing unilateral stellate ganglion blockade for the management of chronic ...
Fagard R - - 1993
Both single dose and short term diuretic treatment adversely affect maximal exercise capacity and the duration of prolonged submaximal exercise. However, insufficient data are available to establish the effect of long term diuretic treatment on exercise capacity. beta-Blockade reduces maximal aerobic power by approximately 7%. In addition, the capacity for ...
MacMathuna P - - 1993
It has been postulated that the adverse metabolic effects of beta-adrenergic blockade with propranolol in cirrhosis may be related to altered delivery and utilisation of oxygen, particularly in patients with advanced alcoholic liver disease (ALD). Consequently, in 10 patients with decompensated ALD, we assessed (a) systemic and hepatic oxygen delivery ...
Wijnen J A - - 1993
Inhibition of adipose tissue lipolysis may be involved in the impairment of endurance capacity after administration of a beta-adrenoceptor blocker. During endurance exercise, no significant decrease in plasma glycerol and free fatty acid (NEFA) concentrations after beta-adrenoceptor blockade is found. However, the levels during recovery from exhaustion are lower after ...
Kubota K - - 1993
The pharmacokinetic profiles of transdermal timolol 6 and 24 mg (as 5 and 20% w/v patches) was studied in four healthy young volunteers. To assess its bioavailability, the pharmacokinetics of an IV infusion of timolol maleate 5 mg was also determined in the same subjects. When the 20% (w/v) timolol ...
van Baak M A - - 1993
Inhibition of adipose tissue lipolysis, leading to a reduced availability of non-esterified fatty acids for energy production in the active skeletal muscles, may be involved in the impairment of endurance exercise capacity after administration of a beta-adrenoceptor blocking agent. The effect of increasing the availability of plasma NEFA during exercise ...
Kraemer W J - - 1993
To examine the changes of plasma beta-endorphin (beta-EP) concentrations in response to various heavy-resistance exercise protocols, eight healthy male subjects randomly performed each of six heavy-resistance exercise protocols, which consisted of identically ordered exercises carefully designed to control for the repetition maximum (RM) resistance (5 vs. 10 RM), rest period ...
Lönnqvist F - - 1992
The existence of lipolytic beta-adrenoceptor (BAR) resistance was investigated in vivo and in isolated abdominal subcutaneous adipocytes in 65 healthy and drug-free subjects. The concentration of isoprenaline (nonselective BAR agonist) causing half-maximum lipolysis effect (ED50) varied bimodally and 10(6)-fold between individuals but was almost constant in the same subject when ...
Bordin D - - 1992
The purpose of this study is to describe the dynamics of carnitine, its esters and beta-hydroxybutyrate, during a prolonged moderate-intensity physical exercise, as the literature data (Angelini 1986, Carlin 1986, Lennon 1984) up to date reported were not uniform. In our study twenty-two untrained subjects (11 males, 11 females) performed ...
Nielson C P - - 1992
Inflammatory processes have potential importance in the pathogenesis of bronchial hyperresponsiveness and asthma. Because beta-adrenoceptor function may be impaired in asthma, we studied regulation of the leukocyte respiratory burst using blood samples from subjects with bronchial hyperresponsiveness to methacholine. Leukocytes from hyperresponsive subjects were less responsive to the beta-agonist isoproterenol ...
Tremblay A - - 1992
This study investigated the contribution of beta-adrenergic stimulation to the increase in resting metabolic rate (RMR) and lipid oxidation observed in exercise-trained individuals. Nine trained and eight sedentary men were subjected to two testing sessions, during which these variables were measured before and for 3 h after the oral administration ...
Walberg-Rankin J - - 1992
The acute effect of weightlifting on beta-endorphin and estradiol was studied in experienced female recreational weightlifters. Five eumenorrheic females completed two months of testing, each with a different sequence of testing conditions (SEQ1 and SEQ2). In SEQ1, a week of weight maintenance diet and prescribed exercise (3 d.wk-1, 3 sets, ...
Mundie T G - - 1992
The mixed adrenergic agonist, epinephrine (10 micrograms/kg, i.v.), the beta-adrenergic receptor antagonist, propranolol (0.2 mg/kg, i.v.), or the alpha-adrenergic receptor antagonist, phenoxybenzamine (1 mg/kg, i.v.), were administered to sheep immediately before maximal incremental exercise. The effects of each of these drugs on hemoglobin (Hb) concentration during maximal exercise and on ...
Brown P H - - 1992
An open, randomized, cross-over study was performed to compare the efficacy and acceptability of two breath-actuated inhalers, the Turbohaler (T) and Diskhaler (D), for delivery of beta-agonists. Thirty six adults with chronic asthma requiring beta-agonists four times daily were treated with terbutaline 500 micrograms via T and salbutamol 400 micrograms ...
Stoschitzky K - - 1992
In-vitro studies have shown that atenolol, a beta-blocking agent, is stereoselectively taken up by and released from adrenergic nerve endings by membrane depolarisation. To investigate the potential importance of these findings, blood samples were taken at rest and after exercise testing from 10 patients (mean [SE] age 60 [3] years) ...
Linderholm H - - 1992
Patients with a hereditary mitochondrial myopathy with succinate dehydrogenase (SDH) deficiency and abnormal lactacidosis during physical exercise have a low work capacity when exercising for about 10-15 min. Their maximum voluntary muscular strength is fairly normal. The relationship between the time (t) and a constant workload (N) that a healthy ...
Rahkila P - - 1992
Concentrations of immunoreactive beta-endorphin and corticotropin in plasma were studied in 27 healthy physically active women at rest and after the exercise test on a treadmill requiring 60% and 90% of the maximal oxygen consumption. Eleven of the subjects were on a combination-type of oral contraceptive pills, and the remaining ...
Bruckmaier R M - - 1992
Calves perorally administered the beta-adrenergic agonist (beta-A) clenbuterol for 28 d were studied before, during, and after a 12-min treadmill exercise. During exercise on d 1 of clenbuterol administration, respiratory rate, respiratory minute volume, and heart rate and blood glucose, lactate, and insulin concentrations increased more in beta-A-treated calves than ...
Stratton J R - - 1992
BACKGROUND: Cardiac aging is characterized by a reduced heart rate response to beta-agonist stimulation with isoproterenol, but whether the ejection fraction and other cardiovascular responses are reduced in humans is largely unknown. In addition, whether reduced beta-agonist responses can be improved with exercise training has not been determined in humans. ...
Symons J D - - 1992
BACKGROUND: Myocardial ischemia is considered to be a possible stimulus for development of the coronary collateral circulation. We therefore hypothesized that chronic reduction of myocardial oxygen demand to lessen ischemia would attenuate coronary collateral development over an 8-week period using left circumflex coronary artery (LCx) ameroid-induced constriction in pigs. METHODS ...
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