Search Results
Results 401 - 450 of 1012
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Oishi Peter - - 2006
Several congenital heart defects require surgery that acutely increases pulmonary blood flow (PBF). This can lead to dynamic alterations in postoperative pulmonary vascular resistance (PVR) and can contribute to morbidity and mortality. Thus the objective of this study was to determine the role of nitric oxide (NO), endothelin (ET)-1, and ...
Luksch Alexandra - - 2006
Angiotensin II and endothelin-1 are potent vasoconstrictors that appear to play a role in retinal blood flow regulation. In the present study, we investigated the possible role of the angiotensin and the endothelin system in the regulation of retinal vessel diameters during isometric exercise in healthy humans. The study design ...
Kuge Naomi - - 2005
In patients receiving hemodialysis, exercise capacity is extremely limited. Although vasodilation is one of the key phenomena for blood perfusion into working skeletal muscles during exercise, it is not clear whether the vasodilator capacity is increased after physical training in this population. We attempted to clarify whether handgrip exercise training ...
Coelho-de-Souza Lívia Noronha - - 2005
The effects of the essential oil of Eucalyptus tereticornis Sm. (EOET) on guinea-pig tracheal smooth muscle were investigated. EOET (10 - 1000 microg/mL) relaxed the tracheal basal tonus with an EC (50) value of 125.3 [52.2 - 300.9] microg/mL. Its maximal relaxation (40 +/- 6 %) was significantly lower than ...
Heylen E - - 2005
We undertook this study to determine whether long-term high intensity exercise would modify cutaneous endothelial-dependent vasodilation. We compared a group of 9 highly trained windsurfers (mean age: 24.5 +/- 1.6 years) to a control group of 8 sedentary individuals (22.9 +/- 0.4 years, NS). Laser Doppler was used to measure ...
Dyson Kenneth S - - 2006
We tested the hypothesis that flow-mediated dilation (FMD) of the brachial artery would be impaired by acute increases in sympathetic nervous system activity (SNA) in models where similar peak shear stress stimulus was achieved by varying the duration of forearm muscle ischemia. Eleven healthy young men were studied under four ...
Heaps Cristine L CL Department of Physiology and Pharmacology, MS4466, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, Texas 77843, USA. - - 2006
Endurance exercise training increases basal active tone in coronary arteries and enhances myogenic tone in coronary arterioles of control animals. Paradoxically, exercise training has also been shown to augment nitric oxide production and nitric oxide-mediated relaxation in coronary arterioles. The purpose of the present study was to examine the effect ...
De Moraes Roger - - 2005
It has been shown previously that high glucose causes direct and acute endothelial dysfunction in non-diabetic isolated rabbit kidney. This study assessed whether exercise training is able to maintain normal renal vascular endothelial function despite high glucose exposure. Animals were pen confined (SED) or treadmill trained over a 12-week period ...
Ogoh Shigehiko - - 2006
The purpose of this study was to examine the hypothesis that the operating point of the cardiopulmonary baroreflex resets to the higher cardiac filling pressure of exercise associated with the increased cardiac filling volumes. Eight men (age 26 +/- 1 yr; height 180 +/- 3 cm; weight 86 +/- 6 ...
Thaman Rajesh - - 2005
OBJECTIVES: We assessed the frequency of abnormal forearm vasodilator responses during lower body negative pressure (LBNP) in 21 non-obstructive hypertrophic cardiomyopathy (HCM) patients (31 +/- 8 [20 to 43] years) with abnormal blood pressure response (ABPR) to exercise and the effects of three drugs used to treat vasovagal syncope (propranolol, ...
Tanriverdi Halil - - 2005
BACKGROUND: Aerobic exercise enhances endothelium-dependent vasodilation in healthy individuals. It is thought that exercise increases nitric oxide (NO) production and decreases NO inactivation, leading to an increase in NO bioavailability. Angiotensin II and NO have important roles in maintaining vascular tone. There are polymorphisms of the angiotensin converting enzyme (ACE) ...
Patel Ayan R - - 2005
BACKGROUND: Vascular endothelial function has been observed to correlate with exercise capacity in predominantly male populations. Gender-based differences exist in the clinical course of coronary artery disease, and previous studies indicate that estrogen may influence endothelial function. These observations raise the possibility that the relationship between endothelial function and exercise ...
Eskurza Iratxe - - 2005
Endothelium-dependent dilatation (EDD) is impaired with ageing in sedentary, but not in regularly exercising adults. We tested the hypotheses that differences in tetrahydrobiopterin (BH(4)) bioactivity are key mechanisms explaining the impairment in EDD with sedentary ageing, and the maintenance of EDD with ageing in regularly exercising adults. Brachial artery flow-mediated ...
VanTeeffelen Jurgen W G E - - 2006
Skeletal muscle blood flow increases rapidly with exercise onset, but little is known of where or how the rapid onset of vasodilation (ROV) is governed within the microcirculation. In the retractor muscle of anesthetized hamsters (n = 26), we tested the following: 1) where in the resistance network ROV occurred, ...
Buckwalter John B - - 2005
Existing evidence suggests that neuropeptide Y (NPY) acts as a neurotransmitter in vascular smooth muscle and is coreleased with norepinephrine from sympathetic nerves. We hypothesized that release of NPY stimulates NPY Y(1) receptors in the skeletal muscle vasculature to produce vasoconstriction during dynamic exercise. Eleven mongrel dogs were instrumented chronically ...
Houweling Birgit - - 2005
We have previously shown that vasodilators and vasoconstrictors that are produced by the vascular endothelium, including nitric oxide (NO), prostanoids and endothelin (ET), contribute to the regulation of systemic and pulmonary vascular tone in swine, in particular during treadmill exercise. Since NO and prostanoids can modulate the release of ET, ...
Girod John P - - 2005
The parasympathetic nervous system facilitates peripheral arterial vasodilation and is also responsible for a decrease in heart rate immediately after exercise (heart rate recovery [HRR]). The relation among parasympathetic tone measured by HRR after exercise, endothelium-mediated vasodilation, and nitroglycerin-mediated vasodilation (determined with brachial artery ultrasound) was assessed in 25 healthy ...
Wilder-Smith Einar P - - 2005
The degree of digit and ulnar reflex vasoconstriction is a useful measure of hand sympathetic function. Reflex vasoconstriction is generally expressed as the percentage of reflex reduction in blood flow compared to resting flow. Sympathetic traffic to and from the hand can be altered by environmental testing factors, and lead ...
Schrage William G - - 2005
ATP released from circulating erythrocytes is a potential signal regulating muscle blood flow during exercise (exercise hyperemia), and intravascular ATP appears to blunt sympathetic vasoconstriction during exercise. Erythrocytes from patients with cystic fibrosis (CF) do not release ATP. The goal of the present study was to determine whether increases in ...
Thijssen Dick H J - - 2005
PURPOSE: Studies investigating vascular adaptations in non-exercised areas during whole body exercise training show conflicting results. Individuals with spinal cord injury (SCI) provide a unique model to examine vascular adaptations in active tissue vs adjacent inactive areas. The purpose of this study is to assess the effects of 4 wk ...
Mochizuki Seiichi - - 2005
Nipradilol (NP: 3,4-dihydro-8-[2-hydroxy-3-isopropylamino]propoxy-3-nitroxy-2H-1-benzopyran) shows not only beta-adrenoreceptor-blocking effects but also nitroglycerin-like vasodilatory action. We aimed to directly measure NP-derived nitric oxide (NO) in the vascular wall. An NO-sensitive microelectrode was inserted into the vascular media (the vasodilatory action site of NO) of isolated perfused canine femoral arteries. Each vessel was ...
Jen Chauying J - - 2005
Chronic exercise in healthy or hypercholesteremic animals for at least two months improves their vascular functions. This study is to examine whether short-term exercise training protocols can correct early-stage vascular dysfunction induced by high-cholesterol diet feeding. Male New Zealand White rabbits were fed for 2, 4 or 6 weeks with ...
Safaya Rakesh - - 2005
BACKGROUND: Lysophosphatidylcholine (LPC) is a product of phosphatidylcholine hydrolysis by phospholipase A(2) and a mediator of the lipid-induced atherosclerotic changes. In this study, we determined the effects of LPC on vasomotor functions, oxidative stress, and endothelial nitric oxide synthase (eNOS) expression in porcine coronary arteries. METHODS: Porcine coronary arteries were ...
Dinenno Frank A - - 2005
Recent evidence indicates that older healthy humans demonstrate greater vasoconstrictor tone in their active muscles during exercise compared with young adults. Therefore, we tested the hypothesis that the normal ability of muscle contractions to blunt sympathetic alpha-adrenergic vasoconstriction (functional sympatholysis) is impaired with age in healthy humans. We measured forearm ...
Ainslie Philip N - - 2005
The relative importance of CO2 and sympathetic stimulation in the regulation of cerebral and peripheral vasculatures has not been previously studied in humans. We investigated the effect of sympathetic activation, produced by isometric handgrip (HG) exercise, on cerebral and femoral vasculatures during periods of isocapnia and hypercapnia. In 14 healthy ...
Allen Jason D - - 2005
The measurement of nitric oxide (NO) bioavailability is of great clinical interest in the assessment of vascular health. However, NO is rapidly oxidized to form nitrite and nitrate and thus its direct detection in biological systems is difficult. Venous plasma nitrite (nM concentrations) has been shown to be a marker ...
Bousquet-Santos K - - 2005
We evaluated vascular reactivity after a maximal exercise test in order to determine whether the effect of exercise on the circulation persists even after interruption of the exercise. Eleven healthy sedentary volunteers (six women, age 28 +/- 5 years) were evaluated before and after (10, 60, and 120 min) a ...
Vanmolkot Floris H M - - 2005
To assess the reproducibility of the forearm blood flow (FBF) response to intra-arterial infusion of calcitonin-gene related peptide (CGRP), measured by venous occlusion plethysmography. In addition, to compare different ways of expressing the FBF response and perform sample size calculations. On two separate visits, CGRP (10 ng min(-1) dl(-1) forearm) ...
Greig Lynn D - - 2005
The influence of vasodilators on augmentation index (AIx) offers a simple, rapid and noninvasive method of evaluating vascular function. Glyceryl trinitrate (GTN) is widely used as an endothelium-independent vasodilator, although other nitrates that are shorter acting may have advantages in clinical studies. The aim of this study was to compare ...
Trombetta Ivani C - - 2005
We hypothesized that the muscle vasodilatation during mental stress and exercise would vary among humans who are polymorphic at alleles 16 and 27 of the beta(2)-adrenoceptors. From 216 preselected volunteers, we studied 64 healthy, middle-aged normotensive women selected to represent three genotypes: homozygous for the alleles Arg(16) and Gln(27) (Arg(16)/Gln(27), ...
Harvey Paula J - - 2005
BACKGROUND: Both exercise and postmenopausal estrogen therapy augment endothelial function. We hypothesized that their interaction would be additive. The study objectives were to determine in postmenopausal women (1) the effects of an acute bout of exercise on brachial artery endothelium-dependent flow-mediated vasodilation (FMD), (2) whether these responses to exercise are ...
Duncker Dirk J - - 2005
Coronary blood flow is tightly coupled to myocardial oxygen consumption to maintain a consistently high level of myocardial oxygen extraction. This tight coupling has been proposed to depend on periarteriolar oxygen tension, signals released from cardiomyocytes (adenosine acting on K+(ATP) channels), and/or the endothelium (prostanoids, nitric oxide, endothelin [ET]) and ...
Lockwood Jennifer M - - 2005
In normally active individuals, postexercise hypotension after a single bout of aerobic exercise is due to an unexplained peripheral vasodilatation. Histamine has been shown to be released during exercise and could contribute to postexercise vasodilatation via H1 receptors in the peripheral vasculature. The purpose of this study was to determine ...
Smith Scott A - - 2005
It has been suggested that nitric oxide (NO) is a key modulator of both baroreceptor and exercise pressor reflex afferent signals processed within the nucleus tractus solitarius (NTS). However, studies investigating the independent effects of NO within the NTS on the function of each reflex have produced inconsistent results. To ...
Donato Anthony J - - 2005
OBJECTIVES: The incidence of cardiovascular disease increases with advancing age. Vascular dysfunction has been linked to cardiovascular disease and aging, although most research has focused on endothelium-dependent vasodilator dysfunction. Another possible mechanism for this vascular dysfunction with aging is enhanced vasoconstrictor responsiveness of the resistance vasculature, and in particular, reactivity ...
Saunders Natasha R - - 2005
We sought to understand the nature of control mechanisms involved in the adaptation of exercising muscle hyperemia. Seven subjects performed rhythmic dynamic forearm exercise under two exercise conditions: small step 1 [step increase from rest to 40% peak forearm vascular conductance (FVC), in ml.min(-1).100 mmHg-1] for 5 min followed by ...
Johnson John M - - 2005
Previous work indicates that sympathetic nerves participate in the vascular responses to direct cooling of the skin in humans. We evaluated this hypothesis further in a four-part series by measuring changes in cutaneous vascular conductance (CVC) from forearm skin locally cooled from 34 to 29 degrees C for 30 min. ...
Hägg Ulrika - - 2004
Forced training has been shown to have beneficial vascular effects in various animal exercise models. In the present study, we explored possible physiological and molecular effects of voluntary physical exercise on various vascular beds. SHR (spontaneously hypertensive rats) performed voluntary exercise for 5 weeks in a computerized wheel cage facility. ...
Chies Agnaldo B - - 2004
This study was performed to determine the effect of forced swimming on the vascular responsiveness of the rat superior mesenteric artery to phenylephrine, focusing on the involvement of locally produced substances. Repeated but not single sessions of forced swimming exercise reduced the vasoconstrictor potency of phenylephrine in the studied arteries, ...
Kindig Angela E - - 2005
Vanilloid type 1 (VR-1) receptors are stimulated by capsaicin and hydrogen ions, the latter being a by-product of muscular contraction. We tested the hypothesis that activation of VR-1 receptors during static contraction contributes to the exercise pressor reflex. We established a dose of iodoresinaferatoxin (IRTX), a VR-1 receptor antagonist, that ...
Donato, Anthony John
Aging is associated with increases in regional and systemic vascular resistance and arterial blood pressure. One possible mechanism through which these age-associated alterations occur is enhanced vasoconstrictor responsiveness, or alterations in the structural properties of the resistance vasculature. We hypothesized that stiffness and vasoconstriction would be greater in skeletal muscle ...
Bisquolo V A F - - 2005
Insulin infusion causes muscle vasodilation, despite the increase in sympathetic nerve activity. In contrast, a single bout of exercise decreases sympathetic activity and increases muscle blood flow during the postexercise period. We tested the hypothesis that muscle sympathetic activity would be lower and muscle vasodilation would be higher during hyperinsulinemia ...
Riksen Niels P - - 2005
OBJECTIVE: Endogenous adenosine has several cardioprotective effects. We postulate that in patients with hyperhomocysteinemia increased intracellular formation of S-adenosylhomocysteine decreases free intracellular adenosine. Subsequently, facilitated diffusion of extracellular adenosine into cells through dipyridamole-sensitive transporters is enhanced, limiting adenosine receptor stimulation. We tested this hypothesis in patients with classical homocystinuria (n=9, ...
Li Na - - 2004
BACKGROUND: Many physiologic (post-prandial hyperemia), pathologic (inflammatory bowel disease), and clinical (enteral feeding) phenomena involve changes in microvascular blood flow to the intestine. Adenosine (Ado) derived from energy metabolism causes vasodilation and appears to be involved in some of these events. The Ado-mediated control mechanisms appear to vary with the ...
Middlekauff Holly R - - 2004
Evidence in healthy animals and humans is accumulating that the muscle mechanoreceptors play an important role in mediating sympathetic activation during exercise, especially rhythmic exercise. Furthermore, muscle mechanoreceptors appear to be sensitized acutely during exercise by metabolic by-products, although the identity of these by-products remains unknown. The purpose of this ...
Hansell Jimmy - - 2004
OBJECTIVE: To compare different non-invasive methods for determination of human endothelial function in peripheral circulation. DESIGN: Observational, cross-sectional study in 39 healthy subjects (21 females, age 17-56 years). SETTING: Vascular research laboratory at university hospital. METHODS: Laser Doppler (LD) flowmetry was used to compare skin microvascular perfusion changes during postocclusive ...
Green Daniel J - - 2005
The contribution of endothelium-derived nitric oxide (NO) to exercise hyperaemia remains controversial. Disparate findings may, in part, be explained by different shear stress stimuli as a result of different types of exercise. We have directly compared forearm blood flow (FBF) responses to incremental handgrip and cycle ergometer exercise in 14 ...
Durand S - - 2004
The participation of prostaglandins (PGs) in the cutaneous vasodilatation to acetylcholine (ACh) applied via iontophoresis is under debate. Using laser Doppler flowmetry, we studied the long lasting effect (20 min) of iontophoretic application (30 s; 0.1 mA) of ACh on the human forearm. Experiments were repeated (1) using deionized water ...
Fadel Paul J - - 2004
Sympathetic vasoconstriction is normally attenuated in exercising muscles of young men and women. Recent evidence indicates that such modulation, termed functional sympatholysis, may be impaired in older men. Whether a similar impairment occurs in older women, and what role oestrogen deficiency might play in this impairment, are not known. Based ...
Wang Jong-Shyan - - 2005
This study investigated how exercise training and detraining affect the cutaneous microvascular function and the regulatory role of endothelium-dependent dilation in skin vasculature. Ten healthy sedentary subjects cycled on an ergometer at 50% of maximal oxygen uptake (VO(2max)) for 30 min daily, 5 days a week, for 8 weeks, and ...
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