At present, several techniques exist that claim to evaluate endothelium-dependent vasodilation (EDV) in the human peripheral circulation. The present study aims to evaluate the relationships between four of these techniques. A group of 24 young, healthy subjects underwent measurements of EDV and endothelium-independent vasodilation (EIDV) in predominately resistance vessels in ...

Chronic cigarette smoking alters coronary vascular endothelial response. To determine whether altered response also occurs in young individuals without manifest coronary disease we quantified coronary blood flow at rest, following adenosine vasodilator stress and during the cold pressor test in healthy young smokers. Myocardial blood flow (MBF) was quantified by ...

BACKGROUND: Cutaneous active vasodilatation is a cholinergic nerve mediated function of the sympathetic nervous system and the disturbed function of cholinergic neurotransmission is known as a prominent feature of Alzheimer's disease (AD). METHODS: To assess this relationship, skin blood flow (SkBF) and other haemodynamic parameters were determined by a simple ...

BACKGROUND: A deficiency of tetrahydrobiopterin (BH4), an essential cofactor for nitric oxide (NO) synthase, decreases NO synthesis and increases superoxide production. Supplementation of BH4 has been postulated to improve endothelial function in atherosclerotic patients. The purpose of this study was to determine whether BH4 restores endothelium-dependent vasodilation in patients with ...

Leptin, a product of the ob gene, plays an important role in the regulation of body fat and has been suggested to cause vasodilation in rats. The purpose of this study was to evaluate whether leptin also has a vasodilating effect in humans. Using a strain-gauge plethysmography, we evaluated forearm ...

The role of endothelial calcium signaling in exercise-enhanced ACh-induced vasorelaxation was examined using male Wistar rats (8~10 wk old) that were divided into control and exercise groups. The exercised animals ran on a treadmill with progressive increments of speed until exhaustion. After decapitation, aortic rings were dissected and loaded with ...

Several cardiovascular disorders, including atherosclerosis, are associated with endothelial dysfunction and enhanced expression of endothelin-1 (ET-1). The role of ET-1 in the development of endothelial dysfunction in vivo remains unclear. The objective of the present study was to investigate the effect of elevated circulating levels of ET-1 on endothelium-dependent vasodilatation ...

Chronic exercise upregulates endothelial nitric oxide synthase (eNOS) gene expression. Whether the expression of inducible nitric oxide synthase (iNOS) is affected by exercise is unknown. We therefore investigated the effects of chronic exercise on iNOS and eNOS expression in isolated rat aortic endothelial and smooth muscle cells separately. Five-week-old male ...

Magnetic resonance (MR) imaging techniques and a custom MR-compatible exercise bicycle were used to measure, in vivo, the effects of exercise on hemodynamic conditions in the abdominal aorta of eleven young, healthy subjects. Heart rate increased from 73 +/- 6.2 beats/min at rest to 110 +/- 8.8 beats/min during exercise ...

Endothelium-dependent vasodilation is impaired in patients with chronic heart failure (CHF). However, the mechanisms responsible for this effect are not fully understood. The vasodilator response to acetylcholine (ACh) has been used to examine the endothelium-dependent vasodilation in humans and is known to be mediated by nitric oxide (NO). The impaired ...

The endothelial dysfunction in cardiological syndrome X has been studied mainly by invasive methods and by measuring vasoactive mediator (nitric oxide (NO), endothelin-1) levels. Other parameters evaluating this dysfunction (defined as an imbalance between vascular relaxing and contracting factors, between procoagulant and anticoagulant or growth-inhibiting and growth-promoting substances) have not ...

Study of the microcirculation by iontophoresis is potentially confounded by any non-specific effects of current application. Laser Doppler flow (LDF, mean +/- SD; arbitrary units; AU) was recorded on the forearms of healthy volunteers during and 20 min following application of 0.10-mA current for 1, 3 and 5 min, using ...

We hypothesized that altered vasoreactivity in perinatal pulmonary hypertension (PH) is characterized by abnormal responses to hemodynamic stress, including the loss of flow-induced vasodilation and an augmented myogenic response. Therefore, we studied the acute hemodynamic effects of brief compression of the ductus arteriosus (DA) in control fetal lambs and in ...

Flow-mediated vasodilatation (FMD) of the brachial artery is used as a measure to quantify endothelial dysfunction. However, FMD after occlusion only is small in healthy people over middle age, but can be increased after handgrip exercise. The aim of this study was to evaluate whether postocclusion vasodilatation after handgrip exercise ...

1. The aims of the present study were to investigate the effects of fresh garlic and one of its active metabolites, allicin, on rat isolated pulmonary arteries (RPA). 2. In endothelium-intact and phenylephrine-precontracted RPA, the addition of a water or a 5% ethanol extract of fresh garlic (1-500 microg/mL) resulted ...

Nebivolol, a racemic mixture of (S,R,R,R) and (R,S,S,S) enantiomers, is the most beta1-selective adrenoceptor antagonist currently available for clinical use. However, its haemodynamic effects differ from those of classical beta-adrenoceptor antagonists as a result of a vasodilating action. Nebivolol is devoid of alpha-adrenergic antagonist actions, and the detailed mechanism of ...

We tested the hypothesis that increases in forearm blood flow (FBF) during the adaptive phase at the onset of moderate exercise would allow a more rapid increase in muscle O2 uptake (VO2 mus). Fifteen subjects completed forearm exercise in control (Con) and leg occlusion (Occ) conditions. In Occ, exercise of ...

OBJECTIVES: We sought to analyze diameter changes of conduit arteries in response to whole-body exercise and hypothesized that this response might be endothelium-dependent and, therefore, impaired in smokers. BACKGROUND: Hyperemia and coincident vasodilation are pivotal mechanisms for meeting the increased metabolic demands of active muscle tissue during physical exercise, but ...

OBJECTIVES: This study was performed to determine whether angiotensin type 1 (AT1) receptor inhibition improves abnormal coronary vasomotion and endothelial dysfunction in patients with atherosclerosis or its risk factors. BACKGROUND: Endothelial dysfunction, an early feature of atherosclerosis, contributes to abnormal vasomotion during stress. Angiotensin II may contribute to endothelial dysfunction ...

To examine effects of static exercise on the arterial baroreflex control of vascular sympathetic nerve activity, 22 healthy male volunteers performed 2 min of static handgrip exercise at 30% of maximal voluntary force, followed by postexercise circulatory arrest (PE-CA). Microneurographic recording of muscle sympathetic nerve activity (MSNA) was made with ...

BACKGROUND: Endothelium-dependent modulation of coronary tone is impaired in the collateral-dependent coronary microcirculation. We used a porcine model of chronic coronary occlusion and collateral development to evaluate the hypothesis that exercise training enhances endothelium-mediated relaxation and increases endothelial nitric oxide synthase (ecNOS) mRNA levels of collateral-dependent microvasculature. METHODS AND RESULTS: ...

OBJECTIVES: The purpose of this study was to examine whether exercise training stimulates a generalized improvement in vascular function in patients with type 2 diabetes mellitus. BACKGROUND: Exercise is often recommended for patients with type 2 diabetes to improve physical conditioning and glycemic control. This study examined the effect of ...

OBJECTIVES: This study was designed to determine the effect of two weeks' treatment with L-arginine on the ratio of plasma L-arginine to asymmetric dimethylarginine (ADMA), oxidative stress, endothelium-dependent vasodilatation to acetylcholine, exercise performance and heart rate variability in men with stable angina. BACKGROUND: The ratio of plasma L-arginine:ADMA has been ...

This study examined the effect of low (25% of maximum voluntary contraction) and high (75% of maximum voluntary contraction) intensity short-term handgrip exercise training on localized vascular function. Forearm blood flow was evaluated in twenty-eight healthy men (age: 23 +/- 4.3) pre- and post-training in both forearms at rest, following ...

1. The purpose of these experiments was to use radiolabelled microspheres to measure blood flow distribution within the brain, and in particular to areas associated with motor function, maintenance of equilibrium, cardiorespiratory control, vision, hearing and smell, at rest and during exercise in miniature swine. Exercise consisted of steady-state treadmill ...

This study was designed to evaluate the effects of an ordinary mixed meal on endothelium-dependent vasodilation. Ten young healthy volunteers were given a mixed meal (minced meat sauce with rice, 900 kcal, 34% of the energy content was fat). In the fasting state, at 60 and 120 min after the ...

We hypothesized that forearm blood flow (FBF) during moderate intensity dynamic exercise would meet the demands of the exercise and that postexercise FBF would quickly recover. In contrast, during heavy exercise, FBF would be inadequate causing a marked postexercise hyperemia and sustained increase in muscle oxygen uptake (VO(2musc)). Six subjects ...

During the menstrual cycle, changes in endothelium-dependent vasodilatation have been demonstrated in conduit vessels in vivo, but responses in resistance vessels have not been studied. The aim of this study was to examine endothelium-dependent vasodilatation, the effects of local nitric oxide synthesis, and alpha-adrenergic constriction in resistance vessels during the ...

1. The aim of the present study was to determine whether anti-oxidant therapy with vitamin E and/or cholesterol-lowering therapy with simvastatin would augment resting forearm blood flow (FBF) and metabolic vasodilation in response to exercise and improve endothelial function in young patients with hypercholesterolaemia. 2. Endothelium-dependent and -independent, nitric oxide ...

Exercise training has reversible beneficial effects on cardiovascular diseases, e.g. hypertension, which may result from a decrease in systemic vascular resistance. The purpose of this study was to investigate possible mechanisms associated with the changes in vascular reactivity in large and small arteries with vasoconstrictors and vasodilators in rats after ...

Previous studies have shown that in dogs performing mild to moderate treadmill exercise, partial graded reductions in hindlimb blood flow cause active skeletal muscle to become ischemic and metabolites to accumulate thus evoking the muscle metaboreflex. This leads to a substantial reflex increase in mean arterial pressure (MAP) mediated almost ...

The hypothesis that baroreceptor unloading during dynamic limits cutaneous vasodilation by withdrawal of active vasodilator activity was tested in seven human subjects. Increases in forearm skin blood flow (laser-Doppler velocimetry) at skin sites with (control) and without alpha-adrenergic vasoconstrictor activity (vasodilator only) and in arterial blood pressure (noninvasive) were measured ...

BACKGROUND: We previously reported that reversible endothelial dysfunction is caused by interferon-alpha therapy (IFN) in patients with chronic hepatitis C. In experimental studies, limb blood flow during exercise is reported to be dependent on endothelium-derived nitric oxide. HYPOTHESIS: The purpose of this study was to confirm the effect of IFN ...

AIM: To observe the effect of change in oxygen tension on the release pattern and nature of endothelium-derived substances in isolated rabbit aorta. METHODS: Isometric contractions and relaxations in isolated rabbit strip were observed in response to changes in oxygen tension and effect of various drugs was noted on them. ...

We investigated possible involvement of the actin cytoskeleton in the regulation of the L-arginine/nitric oxide (NO) pathway in pulmonary artery endothelial cells (PAEC). We exposed cultured PAEC to swinholide A (Swinh), which severs actin microfilaments, or jasplakinolide (Jasp), which stabilizes actin filaments and promotes actin polymerization, or both. After treatment, ...

A marked pressor response to water drinking has been observed in patients with autonomic failure and in the elderly, and has been attributed to sympathetic vasoconstrictor activation, despite the absence of such a pressor response in healthy subjects with intact sympathetic mechanisms. We investigated whether water drinking in normal subjects ...

BACKGROUND: Endothelium-derived nitric oxide is an important mediator of exercise-induced changes in skeletal muscle blood flow. Given the recently documented effects of estrogens on nitric oxide synthase, it is hypothesized that oral contraceptives (OC) containing estrogen would increase nitric oxide production at rest and after endurance exercise. Further, we postulated ...

It is widely assumed that all exercise, regardless of the degree of difficulty or strenuousness, is good (no pain-no gain). In this speculative review of the literature and our research findings we highlight the fact that strenuous exercise taken to the extreme initiates an immune and vascular proinflammatory situation. However, ...

The arterial baroreflex mediates changes in arterial pressure via reflex changes in cardiac output (CO) and regional vascular conductance, and the relative roles may change between rest and exercise and across workloads. Therefore, we quantified the contribution of CO and regional vascular conductances to carotid baroreflex-mediated increases in mean arterial ...

The aim of this study was to investigate local muscle O(2) consumption (muscV(O(2))) and forearm blood flow (FBF) in resting and exercising muscle by use of near-infrared spectroscopy (NIRS) and to compare the results with the global muscV(O(2)) and FBF derived from the well-established Fick method and plethysmography. muscV(O(2)) was ...

Heart transplant patients are reported to have impaired regulation of the microvasculature. The purpose of this study was to investigate the cutaneous blood flow and its reactivity to sodium nitroprusside (vasodilator, Nipride 0.1%) and norepinephrine (vasoconstrictor, Levophed 0.1%) in patients after heart transplantation in comparison to normal healthy individuals. Eighteen ...

The primary focus of this review is to discuss the importance of vascular smooth muscle function in mechanisms underlying exercise hyperemia in skeletal muscle. Important features of exercise hyperemia are presented and include: 1) the large magnitude of increase in blood flow, 2) the pattern of increased blood flow within ...

Attenuation of sympathetic vasoconstriction (sympatholysis) in working muscles during dynamic exercise is controversial. A potential mechanism is a reduction in alpha-adrenergic-receptor responsiveness. The purpose of this study was to examine alpha(1)- and alpha(2)-adrenergic-receptor-mediated vasoconstriction in resting and exercising skeletal muscle using intra-arterial infusions of selective agonists. Thirteen mongrel dogs were ...

The phenomenon of reduced responsiveness of the skeletal muscle arterial vasculature to sympathetic activation during exercise (sympatholysis) remains controversial. The purpose of this study was to examine the vascular effects of sympathoactivation in dynamically exercising skeletal muscle. Mongrel dogs (19-24 kg) were instrumented chronically with transit-time ultrasonic flow probes on ...

The purpose of this study was to investigate the mechanism underlying arteriolar responses to hyperosmolality and to determine the effects of daily exercise on this response. Dilator responses were measured in isolated, cannulated, and pressurized skeletal muscle arterioles. Osmolality was increased from approximately 290 to 330 mosmol/kgH(2)O by adding glucose, ...

This study assessed the hypothesis that increasing cardiac filling pressure (CFP) would enhance contracting muscle blood flow (MBF) by stretching cardiopulmonary baroreceptors and attenuate the increase in plasma lactate concentration ([Lac(-)](p)) during dynamic exercise. Continuous negative-pressure breathing (CNPB) (-15 cmH(2)O) was used to increase the CFP by accelerating the venous ...

The vascular responses to endothelin-1 [ET-1; nonselective endothelin-A and -B (ET(A) and ET(B) agonist)] and sarafotoxin 6c (S6c; ET(B) agonist) were investigated in patients with atherosclerosis. ET-1 and S6c (3, 10 and 30 pmol/min) were infused into the brachial artery while forearm blood flow (FBF) was measured by venous occlusion ...

An acute bout of aerobic exercise results in a reduced blood pressure that lasts several hours. Animal studies suggest this response is mediated by increased production of nitric oxide. We tested the extent to which systemic nitric oxide synthase inhibition [N(G)-monomethyl-L-arginine (L-NMMA)] can reverse the drop in blood pressure that ...

Microvascular corrosion casting was used to assess the effects of thrombin and D609, a phospholipase C inhibitor, on the vascularity of the chick embryo chorioallantoic membrane (CAM). Discs containing vehicle, thrombin or D609 were placed on the CAM of fertilized white Leghorn eggs on Day 9 of gestation and vascularity ...

To determine the relative contributions of endothelial-derived nitric oxide (NO) vs. intravascular nitrogen oxide species in the regulation of human blood flow, we simultaneously measured forearm blood flow and arterial and venous levels of plasma nitrite, LMW-SNOs and HMW-SNOs, and red cell S-nitrosohemoglobin (SNO-Hb). Measurements were made at rest and ...