Search Results
Results 401 - 450 of 1182
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Matthys D - - 1996
The aim of this study was to assess plasma ammonia levels during acute treadmill exercise in dogs after intravenous administration of a single dose of different cardioselective (atenolol) and non-selective (sotalol and propranolol) beta-adrenergic blocking drugs. The experiments were performed on 6 male mongrel dogs (20-25 kg) trained to run ...
Tuininga Y S - - 1995
BACKGROUND: Physical exercise and mental work cause alterations in cardiac autonomic control. beta-Blockers protect the heart against stress, and this effect may be in part centrally mediated. In this context, the lipophilicity of the drug would be clinically relevant. METHODS AND RESULTS: Thirty postinfarct patients were randomized to receive 100 ...
White M - - 1995
The effect of beta-adrenergic receptor downregulation on peak exercise response in patients with heart failure has not been directly investigated. Seventy-two patients with idiopathic dilated cardiomyopathy who had a mean ejection fraction of 23 +/- 1% (mean +/- SEM) and New York Heart Association class II or III symptoms were ...
Madjlessi-Simon T - - 1995
The purpose of this trial was to study the additional anti-ischaemic effects of amlodipine in coronary patients with ambulant ischaemia despite beta-blocker therapy. Beta-blockers are the most effective drug therapy for reducing the frequency and duration of ambulatory ischaemic episodes. However, the therapeutic advantage of combined calcium antagonist-beta-blocker treatment remains ...
Schneider D A - - 1995
The purpose of the present study was to examine the relationship between minute ventilation (VE) and plasma concentrations of epinephrine (EPI) and norepinephrine (NE) during incremental cycling (20 W.2 min-1) performed under conditions of beta-adrenergic blockade (80 mg of propranolol) and placebo in six untrained male subjects. No significant differences ...
Holubarsch C - - 1995
BACKGROUND: DL-Sotalol has class III antiarrhythmic activity through prolongation of the repolarization phase of the action potential as well as beta-adrenoceptor-blocking properties. Although the former effect was found to exert positive inotropic effects in animal experimental studies, the latter may be detrimental in heart failure due to negative inotropism. In ...
Thompson J M - - 1995
Dopamine-beta-hydroxylase (D beta H) is the enzyme responsible for intraneural conversion of dopamine to norepinephrine. Its deficiency results in failure of norepinephrine synthesis, excessive dopamine release and orthostatic hypotension. We studied a young patient with this deficiency using the currently available methods to assess sympathetic function namely measurement of norepinephrine ...
Benthem L - - 1995
The influence of 48 hours of starvation on sympathoadrenal regulation of nutrient utilization was investigated in rats. To assess the role of alpha- and beta-adrenoceptors, rats were studied during alpha- and beta-blockade. Energy metabolism was measured using indirect calorimetry before, during, and after moderate swimming exercise (approximately 60% maximal O2 ...
Schrauwen P - - 1995
beta-Adrenoceptor blocking agents impair endurance exercise performance in healthy subjects and in patients with hypertension. A possible explanation for the reduced exercise tolerance is a diminished availability of plasma non-esterified fatty acids (NEFA) for energy production during exercise. This study investigated the effect of beta-adrenoceptor blockade on NEFA uptake of ...
Patel J J - - 1995
OBJECTIVES: This study was designed to assess the effects of beta-blockade on cardiopulmonary exercise performance in symptomatic patients with tight mitral stenosis in sinus rhythm. BACKGROUND: The role of beta-blockers in these patients has been controversial and assessment of effort tolerance using treadmill exercise time has produced conflicting results. METHODS: ...
Matthys D - - 1995
The purpose of the present study was to document exercise induced hyperammoniemia after blockade of the beta-adrenoceptors and to investigate the effect of administration of branched-chain amino acids (BCAA) and glucose in these conditions. Seven dogs, chronically instrumented with a catheter in the deep jugular vein and a Doppler probe ...
Pennacchio M - - 1995
An aqueous extract obtained from the leaves of the traditional Aboriginal medicinal plant Eremophila alternifolia R.Br. (Myoporaceae) was tested on isolated hearts of normotensive rats using the Langendorff heart preparation. A single injection of the extract into the retrograge perfusion solution induced cardioactivity, consisting of a short initial increase in ...
Epple H J - - 1995
In vivo electrogenic Na+ absorption (JeNa) in the human rectum is controlled by acute variation of aldosterone in nanomolar concentration range. In this study we report both the induction of JeNa in human rectum epithelium by nanomolar aldosterone added in vitro and the enzymatic control of glucocorticoid action on JeNa. ...
Silke B - - 1995
1. This study used a continuous-wave echo-Doppler method (Exerdrop) to investigate the effects of beta-adrenoceptor antagonism and partial agonism on cardiovascular responses at rest and during dynamic exercise. 2. A double-blind, randomised, placebo controlled comparison of metoprolol (50 mg) and celiprolol (200 mg) was undertaken in nine normal volunteers; single ...
Geers R - - 1995
Pigs were selected at random from three genetic lines (homozygote halothane positive and negative, heterozygotes), and were transported twice. Before and after each transport, blood samples were taken from the jugular vein to measure plasma cortisol and beta-endorphin content. During each transport behaviour and heart rate of the pigs were ...
Ashcom T L - - 1995
beta-blocker therapy for mitral stenosis is controversial. This study compares right and left heart hemodynamics at rest and supine submaximal exercise in patients (n = 7) receiving chronic beta-antagonists with untreated patients (n = 17) matched for age (mean +/- SD = 51 +/- 12 years) and valve area (0.7 ...
Lamont L S - - 1995
The purpose of this study was to assess the interaction between beta-blockade and exercise on amino acid kinetics. This was a three-way crossover experiment using beta 1-blockade, beta 1,beta 2-blockade, and a placebo control. Three 6-h L-[1-13C]leucine and L-[alpha-15N]lysine infusions were performed. The first 3 h established an isotopic steady ...
Stoschitzky K - - 1995
OBJECTIVE: In vitro studies have shown that, like catecholamines, both propranolol and atenolol are taken up by and released from adrenergic cells. We performed this study to investigate whether this may also play a role in humans and whether stereoselective aspects are important. METHODS: This was a randomized, double-blind, placebo-controlled, ...
Yoshimoto K - - 1995
1. Studies using human liver microsomes and six recombinant human CYP isoforms (i.e. CYP1A2, 2A6, 2B6, 2D6, 2E1 and 3A4) were performed to identify the cytochrome P450 (CYP) isoform(s) involved in the ring 4-hydroxylation and side-chain N-desisopropylation of propranolol enantiomers in humans. 2. alpha-Naphthoflavone and 7-ethoxyresorufin (selective inhibitors of CYP1A1/2) ...
Lyden M - - 1995
We compared the systemic beta-adrenoceptor blockade elicited by metipranolol with timolol in a randomized, double-masked, multiple crossover study in 24 healthy volunteers. On each of 4 test days, subjects exercised on a treadmill for 10 min at 4 mi/h at a 5% gradient. After a 30-min rest, they received one ...
Vyssoulis G P - - 1995
To assess the effect of beta-blocker antihypertensive therapy on exercise capacity, 40 patients randomized to celiprolol 200 mg and metoprolol 100 mg daily in a double-blind fashion were studied after a month of placebo and a year of active treatment. Both drugs normalized office blood pressure and produced echocardiographic and ...
Leenen F H - - 1995
BACKGROUND: In healthy human hearts, beta 2-receptor-mediated chronotropic and inotropic responses contribute to the cardiac responses to beta-agonists. A (patho)physiological relevance for beta 2-receptor-mediated responses has so far not been demonstrated, in part because beta 1-receptor-mediated responses to cardiac neuronally released norepinephrine can mask beta 2-receptor-mediated responses. METHODS AND RESULTS: ...
Benthem L - - 1995
alpha- and beta-adrenoceptors play a key role in the regulation of nutrient supply to working muscles during exercise. To assess their influence in the regulation of substrate utilization, rats were studied during alpha- or beta-adrenoceptor blockade. Energy metabolism was studied by means of indirect calorimetry before, during, and after moderate ...
Grove A - - 1995
BACKGROUND: Salbutamol exhibits partial agonist/antagonist activity at airway beta 2 receptors in vitro in that it attenuates the bronchorelaxant effect of the full agonist isoprenaline. The aim of the present study was to characterise the partial beta 2 agonist/antagonist activity of salbutamol in vivo during supine rest and exercise, in ...
Gullestad L - - 1995
The effect of propranolol (0.15 mg/kg body wt) on K+ fluxes was investigated in seven healthy males performing 8-min two-legged knee-extension exercise at two different powers. K+ concentration was measured in the femoral vein by a K(+)-selective electrode, and leg blood flow was measured by the dye-dilution technique. During control ...
Johnson J A - - 1995
Previous studies have suggested that racial differences may exist in beta-adrenoceptor-mediated responsiveness. However, no clear conclusions can be drawn based on these studies because of the confounding effect of the parasympathetic nervous system on responses to isoproterenol bolus doses. In this study, we blocked the effects of the parasympathetic nervous ...
Menescal-de-Oliveira L - - 1995
Microinjection of carbachol into the dorsal parabrachial regio (PBRd) of guinea pigs induces analgesia from the 5th to the 15th min postinjection, as evaluated by the reduction of the vocalization in response to an electric shock applied to one paw. When reversible blockade of the dorsomedial medulla or specifically of ...
Mott A A - - 1995
This study investigated the effects of exercise on the intrahemispheric coherence of human electroencephalographic (EEG) signals. The frontal and temporal sites of each hemisphere (left: F3, T3; right: F4, T4) were selected as the sites to be compared. The subjects were divided into an exercise group and a control (nonexercise) ...
Viru A - - 1995
beta-Endorphin is metabolized to gamma- and alpha-endorphin. In order to evaluate endorphin metabolism during exercise, radioimmunoassay blood levels of alpha-, beta- and gamma-endorphins were recorded during exercise for 2 h on a cycling ergometer in 12 endurance-trained and 11 untrained male subjects. In untrained subjects, mild exercise (49 +/- 4% ...
Rønnevik P K - - 1995
The effects of the beta 1-selective beta-adrenergic blocker metoprolol on physiological responses, exercise capacity and gas exchange parameters were measured in healthy men using different graded bicycle exercise protocols on separate days before and following administration of 200 mg controlled-release metoprolol. Eleven men performed in randomised order maximal cardiopulmonary exercise ...
Convertino V A - - 1995
Increased sensitivity of end-organ responses to neuroendocrine stimuli as a result of prolonged exposure to the relative inactivity of microgravity has recently been hypothesized. This notion is based on the inverse relationship between circulating norepinephrine and beta-adrenoreceptor sensitivity. Beta-adrenoreceptor activity is reduced in individuals who have elevated plasma norepinephrine as ...
Karita M - - 1995
The effects of a combination regimen of metoprolol and beta 1-adrenoceptor agonist denopamine on resting and exercise heart rate have been studied in 10 normal volunteers. Maximal ramp upright bicycle exercise was performed three times at 1-week intervals. Two hours before each exercise test, 5 mg metoprolol plus 20 mg ...
Cosenzi A - - 1995
Nonselective beta-blockers may reduce exercise performance, not only through hemodynamic but also through metabolic effects. During prolonged physical exertion, lipolysis induced by plasma epinephrine occurs through beta-adrenoceptors of adipocytes. Therefore, beta-blockade may reduce release of free fatty acids (FFA) from adipocytes and consequently the energy supply for muscle cells. In ...
Gleerup G - - 1995
The effects of isradipine and atenolol on platelet function and fibrinolytic activity were studied in 10 male patients with mild untreated hypertension. After a 2-week placebo run-in period, the volunteers were randomized to either isradipine 2.5 mg twice daily or atenolol 100 mg daily for a 6-month period. Those initially ...
Hird R B - - 1994
The use of protamine sulfate in patients has been associated with circulatory collapse and is suspected to directly depress left ventricular function. However, the cellular basis for these changes that occur after protamine administration are unknown. Accordingly, the first objective of this study was to determine the direct effects of ...
Santostasi G - - 1994
Long-term treatment with beta-adrenergic blocking drugs has been shown to induce clinical amelioration in patients with chronic heart failure. However, the efficacy of these agents has not been consistent, and the mechanisms of their beneficial effects remain to be established. The present study evaluated the influence of oral metoprolol on ...
Head A - - 1994
1. Exercise and beta-adrenoceptor blockade have important roles in the prevention and treatment of cardiovascular disease, but fatigue and a reduced capacity to exercise are commonly reported side effects of beta-adrenoceptor blockers. The reduced capacity to exercise may be partly caused by a reduction in fat metabolism. 2. We investigated ...
Art T - - 1994
Ten horses underwent a standardised strenuous treadmill exercise test, before, during and after which measurements were made of plasma beta-endorphin and cortisol concentrations, blood lactate, glucose, haemoglobin and pH, the activities of creatine kinase, lactate dehydrogenase and aspartate amino-transferase, and heart rate, oxygen uptake and expired minute volume. The correlations ...
Takahashi T - - 1994
We assessed the effects of calcium ion (Ca++) entry blockade (nifedipine) on the static elastic properties of the thoracic descending aorta in 60 subjects classified into 4 groups according to age and complications. The stiffness index (beta), which expresses the mechanical properties of the arterial wall, was calculated from the ...
De Mey C - - 1994
A protocol is presented for supine bicycle ergometry in healthy subjects, which aims for a target increase of heart rate (HR = 140 beats min-1) after 4 min cycling under constant load. The required load is selected from a pre-study ergometry with stepwise increasing load. Repeated testing with this protocol ...
Ahmed M W - - 1994
OBJECTIVES: The aim of this study was to evaluate and compare the effects of physiologic and pharmacologic sympathetic stimulation on time and frequency domain indexes of heart rate variability. BACKGROUND: Measurements of heart rate variability have been used as indexes of sympathetic tone. To date, the effects of circulating catecholamines ...
Harris A - - 1994
PURPOSE: To understand those factors that determine the decrease in intraocular pressure (IOP) that occurs during acute dynamic exercise. METHODS: Three aspects of the exercise-IOP relationship were studied. These included graded exercise, with and without CO2 addition for isocapnia; comparison of the IOP response of trained and sedentary subjects to ...
Jones R D - - 1994
A treatment-by-subjects design was used to identify and characterize quantitative electroencephalography (qEEG) changes, at rest and under stimulus conditions, in Beagle dogs given 3 dose levels of atropine sulfate. In general, total power, absolute delta and theta amplitudes increased, while relative beta contribution and spectral frequency 90 decreased, as increased ...
Schneider D A - - 1994
The purpose of the present study was to examine the relationship of plasma potassium (K+) and minute ventilation (VE) during incremental cycling (20 W/2 min) under conditions of beta-adrenergic blockade (80 mg of propranolol) and placebo in six untrained male subjects. No significant differences existed between treatments in O2 uptake, ...
Taylor D V - - 1994
Elevated blood levels of beta-endorphin have been associated with high-intensity exertion, but the stimulus for beta-endorphin release is unknown. Some studies of exercise have associated beta-endorphin release with increased exertion levels, but other evidence suggests that acidosis may stimulate the release of beta-endorphin. This study examines acidosis as a possible ...
Pierce E F - - 1994
Previous research investigating the response of plasma beta-endorphins (beta-EP) to resistance exercise has resulted in equivocal findings. To examine further the effects of resistance exercise on beta-EP immunoreactivity, 10 male and 10 female college-age students participated in a series of controlled isotonic resistance exercises. The session consisted of three sets ...
Wang S Y - - 1994
BACKGROUND: Cardiovascular responses to the adrenergic stimulation are depressed in clinical and experimental endotoxemia. However, the effect of Escherichia coli endotoxemia on coronary microvascular beta-adrenergic function remains to be determined. The purpose of the present study was to test the hypothesis that endotoxemia impairs the beta-adrenoceptor- and adenosine 3'5'-cyclic monophosphate-mediated ...
Rueckert P A - - 1994
We tested the hypothesis that celiprolol, a beta-1 adrenoceptor antagonist with the ancillary property of beta-2-mediated vasodilation, would increase blood flow to active muscles during exercise and result in less impairment of exercise performance compared with the beta-1 antagonist atenolol. After an initial 3-wk washout phase, 11 untrained hypertensive men ...
Van Baak M A - - 1994
To investigate the effect of glucose (Glc) infusion on endurance performance after beta-adrenoceptor blockade, eight healthy male volunteers performed four endurance cycle ergometer tests at 67% of maximal work load after 80 mg of propranolol (Pr) or placebo (Pl) were administered orally in combination with a continuous infusion of Glc ...
Neustein S M - - 1994
Dopexamine hydrochloride (Dopacard) is the novel synthetic catecholamine designed for use in the acute management of a low cardiac output status. In addition to dopaminergic receptor stimulation, dopexamine hydrochloride is a potent beta 2 adrenoceptor agonist with negligible direct beta 1 and no alpha adrenergic effect. The objective of this ...
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