Search Results
Results 451 - 500 of 1003
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Tokizawa Ken - - 2004
We investigated whether selective muscle mechanoreceptor activation in the lower limb opposes arm muscle metaboreceptor activation-mediated limb vasoconstriction. Seven subjects completed two trials: one control trial and one stretch trial. Both trials included 2 min of handgrip and 2 min of posthandgrip exercise muscle ischemia (PEMI). In the stretch trial, ...
Buckwalter John B - - 2004
There is evidence that neuropeptide Y (NPY) acts as a neurotransmitter in vascular smooth muscle and is released with norepinephrine from sympathetic nerves. We hypothesized that NPY Y(1) receptor stimulation would produce vasoconstriction in resting and exercising skeletal muscle. Nine mongrel dogs were instrumented chronically with flow probes on the ...
Clifford Philip S - - 2004
Skeletal muscle blood flow is closely coupled to metabolic demand, and its regulation is believed to be mainly the result of the interplay of neural vasoconstrictor activity and locally derived vasoactive substances. Muscle blood flow is increased within the first second after a single contraction and stabilizes within approximately 30 ...
Togni Mario - - 2004
BACKGROUND: Intracoronary radiotherapy (brachytherapy) has been proposed as treatment option for in-stent restenosis. Long-term results of brachytherapy with regard to vascular integrity and vasomotor responsiveness are unknown. The purpose of the present study was to determine the vasomotor response after brachytherapy and to assess its influence on vasomotion during exercise. ...
Henderson Kyle K - - 2004
Because hypercholesterolemia can attenuate endothelial function and exercise training can augment endothelial function, we hypothesized that exercise training would improve endothelial function of coronary arterioles from pigs in the early stages of cardiovascular disease induced by a high-fat, high-cholesterol (HF) diet. Yucatan miniature swine were fed a normal-fat (NF) diet ...
Vona M - - 2004
BACKGROUND: There is evidence that aerobic exercise improves endothelial function in healthy subjects as well as in patients with chronic heart failure. However, it is unknown whether this effect occurs in patients with recent myocardial infarction (AMI). METHODS: Fifty-two patients with a recent first uncomplicated AMI underwent endothelial function evaluation ...
Saunders Natasha R - - 2004
Controversy exists regarding the contribution of a rapid vasodilatory mechanism(s) to immediate exercise hyperemia. Previous in vivo investigations have exclusively examined rest-to-exercise (R-E) transitions where both the muscle pump and early vasodilator mechanisms may be activated. To isolate vasodilatory onset, the present study investigated the onset of exercise hyperemia in ...
Green Daniel J - - 2004
Exercise training improves vascular function in subjects with cardiovascular disease and risk factors, but there is mounting evidence these vascular adaptations may be vessel bed specific. We have therefore examined the hypothesis that exercise-induced improvements in conduit vessel function are related to changes in resistance vessel function. Endothelium-dependent and -independent ...
De Moraes Roger - - 2004
Exercise training is known to improve vasodilating mechanisms mediated by endothelium-dependent relaxing factors in the cardiac and skeletal muscle vascular beds. However, the effects of exercise training on visceral vascular reactivity, including the renal circulation, are still unclear. We used the experimental model of the isolated perfused rabbit kidney, which ...
Egan Colin G - - 2004
The impact of chronic joint inflammation on articular vascular function in rats was investigated to address whether joint swelling and the associated vascular dysfunction are dependent upon a common prostanoid mechanism. Urinary nitrate/nitrite (NO(x)) and PGE(2) excretion, knee joint diameter and body weight were measured following induction of adjuvant-induced arthritis ...
Lenasi Helena - - 2004
PURPOSE: To investigate whether regular intense physical training induces changes in microvascular reactivity of human glabrous and nonglabrous skin. METHODS: Subjects were physically trained competitive cyclists (N = 19) and age-matched sedentary controls (N = 20). We measured cutaneous microvascular blood flow on the dorsum of the hand (nonglabrous skin) ...
Röszer Tamás - - 2004
During dormancy of terrestrial snails, the whole neuromodulation of the nervous system is deeply modified. In this work we studied the adaptation of a previously described, putatively nitric oxide (NO) forming enteral network to the long-term resting periods of the snail Helix lucorum. The standard NADPH diaphorase (NADPHd) technique, which ...
Schrage William G - - 2004
We tested the hypothesis that inhibition of synthesis of either nitric oxide (NO) or vasodilating prostaglandins (PGs) would not alter exercise hyperaemia significantly, but combined inhibition would synergistically reduce the hyperaemia. Fourteen subjects performed 20 min of moderate rhythmic forearm exercise (10% maximal voluntary contraction). Forearm blood flow (FBF) was ...
Inai Kei - - 2004
To elucidate the relation between exercise capacity and peripheral hemodynamics in patients after the Fontan operation, near-infrared spectroscopy was performed on the vastus lateralis muscle, and flow-mediated vasodilation of the brachial and posterior tibial arteries was done with high-resolution ultrasonography. In Fontan patients, diminished exercise capacity was related to a ...
Buckwalter John B - - 2004
The production of nitric oxide is the putative mechanism for the attenuation of sympathetic vasoconstriction (sympatholysis) in working muscles during exercise. We hypothesized that nitric oxide synthase blockade would eliminate the reduction in alpha-adrenergic-receptor responsiveness in exercising skeletal muscle. Ten mongrel dogs were instrumented chronically with flow probes on the ...
Spier Scott A - - 2004
Ageing reduces endothelium-dependent vasodilatation in humans and animals, and in humans, exercise training reverses the ageing-associated reduction in endothelium-dependent vasodilatation. The purpose of this study was to determine the mechanism(s) by which 10-12 weeks of treadmill exercise enhances endothelium-dependent vasodilatation in muscles of differing fibre composition from young and old ...
Hayward Reid - - 2004
PURPOSE: Although evidence is accumulating that suggests regular moderate physical activity improves physiological and psychological well-being of cancer patients undergoing chemotherapy, the mechanisms involved remain unclear. Therefore, the purpose of this study was to determine if exercise training improves endothelium-dependent vasodilation after exposure to the chemotherapeutic agent 5-fluorouracil (5-FU). METHODS: ...
Moyna N M - - 2004
Endothelial dysfunction occurs early in the atherosclerosis in response to elevated atherosclerotic risk factors, and endothelial dysfunction itself may exacerbate the atherosclerotic process. Treatments that reduce atherosclerotic risk factors also generally improve endothelial function. The present review seeks to summarize the effect of exercise training on endothelial function in human ...
Rendal Vázquez Maria Esther - - 2004
An established method for cryopreservation that might preserve the vascular and endothelial responses of human femoral arteries (HFAs) to be transplanted as allografts was studied. HFAs were harvested from multiorgan donors and stored at 4 degrees C in saline solution before cryostorage. Thirty HFA rings were isolated and randomly assigned ...
Huang Po-Hsun - - 2004
Attenuated heart rate recovery after graded exercise, which is associated with decreased vagal activity, is a powerful predictor of overall mortality. Endothelial function plays a key role in determining the clinical manifestations of established atherosclerotic lesions and has shown to be suppressed by increased sympathetic tone. We designed this study ...
Wray D Walter - - 2004
The mechanisms underlying metabolic inhibition of sympathetic responses within exercising skeletal muscle remain incompletely understood. The aim of the present study was to test whether alpha(2)-adrenoreceptor-mediated vasoconstriction was more sensitive to metabolic inhibition than alpha(1)-vasoconstriction during dynamic knee-extensor exercise. We studied healthy volunteers using two protocols: (1) wide dose ranges ...
Maeda Seiji - - 2004
Vascular endothelial cells produce endothelin (ET)-1, a potent vasoconstrictor peptide, and nitric oxide (NO), a potent vasodilator substance. There are interactions between ET-1 and NO. Exercise results in a marked decrease in renal blood flow. We previously reported that exercise causes an increase of ET-1 production in the kidney, whereas ...
Hirooka Yoshitaka - - 2003
Endothelial dysfunction might be related to an increase in superoxide anion production in patients with hypertension, hypercholesterolemia, diabetes mellitus, and heart failure. Studies in animal models indicate that angiotensin II increases superoxide anion production by vascular tissues. We examined whether angiotensin II attenuates endothelium-dependent vasodilation via an increase in superoxide ...
Data Sheri A - - 2003
BACKGROUND: The purpose of the present study was to determine interactive and main effects of the eNOS T-786C gene polymorphism and habitual physical activity level on forearm vascular resistance (FVR) and forearm blood flow (FBF) at rest and during 3 min of reactive hyperemia. METHODS: We studied healthy, Caucasian (age ...
Sato Atsushi - - 2003
We tested whether reactive oxygen species (ROS) generated from treatment with xanthine (XA) and xanthine oxidase (XO) alter vascular tone of human coronary arterioles (HCA). Fresh human coronary arterioles (HCA) from right atrial appendages were cannulated for video microscopy. ROS generated by XA (10(-4) M) + XO (10 mU/ml) dilated ...
Leuenberger Urs A - - 2003
BACKGROUND: Exercise activates the sympathetic nervous system as a function of the type and intensity of exercise and of the target organ studied. Although central command and activity of metabolically sensitive afferents from exercising muscle are the principal determinants of sympathetic outflow directed to skeletal muscle, the mechanisms that govern ...
Wang Dan - - 2003
The hypothesis that O(2)(.-) enhances angiotensin II (AngII)-induced vasoconstriction and impairs acetylcholine-induced vasodilation of afferent arterioles (Aff) in AngII-induced hypertension was investigated. Rabbits (n = 6 per group) received 12 to 14 d of 0.154 M NaCl (Sham), subpressor AngII (60 ng/kg per min; AngII 60) or slow pressor AngII ...
Osada Takuya - - 2003
Post-exercise related time course of muscle oxygenation during recovery provides valuable information on peripheral vascular disease. The purpose of the present study was to examine post-exercise hyperemia (forearm blood flow; FBF, Doppler ultrasound) assessed by peak FBF, excess FBF and the time constant for FBF (FBF(Tc)) following isometric handgrip exercise ...
Boegli Yann - - 2003
Endurance training modifies the thermoregulatory control of skin blood flow, as manifested by a greater augmentation of skin perfusion for the same increase in core temperature in athletes, in comparison with sedentary subjects. In this study, we tested the hypothesis that a component of this adaptation might reside in a ...
Persson Johan - - 2003
Based on a proposed increase in the release of the vasodilators nitric oxide (NO) and prostacyclin during exercise, and the fact that these substances have vascular permeability-reducing properties, this study was designed to evaluate (1) possible effects of exercise on hydraulic permeability, (2) whether permeability and muscle swelling are reduced ...
Kayikcioglu Meral - - 2003
AIMS: The pathophysiological mechanism in cardiac syndrome-X (anginal chest pain, positive exercise test, and angiographically normal coronary arteries) has been suggested as an impairment in normal endothelial function of the coronary microvasculature, resulting in inadequate flow reserve. The aim of this study was to determine whether statins with proven beneficial ...
Tschakovsky M E - - 2004
We tested the hypothesis that rapid vasodilation proportional to contraction intensity contributes to the immediate (first cardiac cycle after initial contraction) exercise hyperemia. Ten healthy subjects performed single 1-s isometric forearm contractions at 5, 10, 15, 20, 30, 50, and 70% maximal voluntary contraction intensity (MVC) in arm above heart ...
Merkus Daphne - - 2004
Prostacyclin and nitric oxide (NO) are produced by the endothelium in response to physical forces such as shear stress. Consequently, both NO and prostacyclin may increase during exercise and contribute to metabolic vasodilation. Conversely, NO has been hypothesized to inhibit prostacyclin production. We therefore investigated the effect of cyclooxygenase (COX) ...
Buckwalter John B - - 2004
Although there is evidence that sympathetic nerves release ATP as a neurotransmitter to produce vasoconstriction via P2X purinergic receptors, the role of these receptors in the regulation of blood flow to exercising skeletal muscle has yet to be determined. We hypothesized that there is tonic P2X receptor-mediated vasoconstriction in exercising ...
Bariskaner H - - 2003
In this in vitro study on the human umbilical artery, the effects of N(omega)-nitro-L-arginine methyl ester (L-NAME), indomethacin, prazosin, yohimbine and propranolol on the responses induced by bupivacaine and ropivacaine were investigated. Arteries isolated from umbilical cords from women who did not exhibit systemic diseases, who were not on medication ...
Walsh Jennifer H - - 2003
AIMS: Despite the importance of both lipid metabolism and physical activity to cardiovascular health, few studies have examined the effect of exercise training on vascular function in hypercholesterolaemic humans. METHODS AND RESULTS: A randomized, cross-over design investigated the effect of 8 weeks of combined aerobic and resistance exercise training on ...
Hayward Reid - - 2003
Hyperhomocysteinemia is an independent risk factor for the development of cardiovascular disease. Exposure of endothelial cells to elevated levels of homocysteine (HCY) results in decreased availability of nitric oxide (NO) and impaired vascular function, both of which are early events in atherogenesis. Exercise training improves vascular function by increasing endothelial ...
Dinenno Frank A - - 2003
We tested the hypothesis that nitric oxide (NO) is responsible for blunting sympathetic alpha-adrenergic vasoconstriction in the active muscles of humans (functional sympatholysis). We measured forearm blood flow (Doppler ultrasound) and calculated the reductions in forearm vascular conductance (FVC) in response to alpha-adrenergic receptor stimulation during rhythmic handgrip exercise and ...
Green Daniel J - - 2003
We have pooled data from a series of our exercise training studies undertaken in groups with a broad range of vascular (dys) function to the examine the hypothesis that exercise-induced improvements in the conduit and/or resistance vessel function are related to improvements in risk factors for cardiovascular (CV) disease. Endothelium-dependent ...
Granberry Mark C - - 2003
STUDY OBJECTIVE: To compare brachial artery flow-mediated dilation (FMD) in subjects who use smokeless tobacco, smoke cigarettes, or do not use any tobacco product. DESIGN: Cross-sectional study. SETTING: University-affiliated outpatient clinic. SUBJECTS: Seventeen apparently healthy volunteers who for more than 1 year smoked at least 10 cigarettes/day, used at least ...
Goto Chikara - - 2003
BACKGROUND: Aerobic exercise enhances endothelium-dependent vasodilation in hypertensive patients, patients with chronic heart failure, and healthy individuals. However, it is unclear how the intensity of exercise affects endothelial function in humans. The purpose of the present study was to determine the effects of different intensities of exercise on endothelium-dependent vasodilation ...
Pesić Srdan - - 2003
The effects of noradrenaline (Nor) and phenylephrine (Phe) on the isolated, non-precontracted perforating branch of the human internal mammary artery (HIMA) were investigated. Nor and Phe induced concentration-dependent contractions of intact and endothelium-denuded arterial rings with no statistically significant differences between the pEC(30) and maximal response values. The pretreatment of ...
Hambrecht R - - 2003
In stable coronary artery disease (CAD), exercise training has well-documented positive effects on arterial endothelial function. NO derived from endothelial NO synthase (eNOS) is regarded as a protective factor against atherosclerosis. The aim of the present study was to investigate the effects of exercise training on the endothelial function in ...
Ersoz G - - 2003
The aim of this study was to investigate the impact of acute exercise on portal blood flow in liver transplant recipients compared to healthy subjects since it is known that transplantation produces a denervated liver and intrahepatic vascular tube. Twelve liver transplantation recipients and 12 age-gender-matched subjects were included in ...
Kenny Glen P - - 2003
The hypothesis that exercise causes an increase in the postexercise esophageal temperature threshold for onset of cutaneous vasodilation through an alteration of active vasodilator activity was tested in nine subjects. Increases in forearm skin blood flow and arterial blood pressure were measured and used to calculate cutaneous vascular conductance at ...
Studinger Péter - - 2003
Arterial baroreflex function is altered by dynamic exercise, but it is not clear to what extent baroreflex changes are due to altered transduction of pressure into deformation of the barosensory vessel wall. In this study we measured changes in mean common carotid artery diameter and the pulsatile pressure : diameter ...
Buckwalter John B - - 2003
There is evidence that ATP acts as a neurotransmitter in vascular smooth muscle and is coreleased with norepinephrine from sympathetic nerves. We hypothesized that P2X-receptor stimulation with the selective P2X-receptor agonist alpha,beta-methylene ATP would produce vasoconstriction in resting and exercising skeletal muscle. Six mongrel dogs were instrumented chronically with flow ...
Kvandal Per - - 2003
Nitric oxide (NO) and prostaglandines (PGs) are important in regulation of vascular tone and blood flow. Their contribution in human cutaneous circulation is still uncertain. We inhibited NO synthesis by infusing N(G)-monomethyl-L-arginine (L-NMMA) in the brachial artery (16 micromol/min for 5 min) and reversed it by intraarterial infusion of L-arginine ...
Sheriff Don D - - 2003
Previous studies examining the delay to the onset of vasodilation have primarily focused on the onset of exercise, a setting complicated by the fact that the muscle pump and the vasodilator systems are both activated, making it difficult to attribute changes in blood flow to one or both. The goal ...
Jacob Giris - - 2003
BACKGROUND: Despite the widespread use of tyramine as a pharmacological tool to assess the effects of norepinephrine release from sympathetic nerve terminals, its vascular effects are not adequately characterized. In particular, previous results indicate that intravenous tyramine produces little if any systemic vasoconstriction, suggesting that tyramine does not cause significant ...
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